1 December 2009

Gran Tierra Energy Announces Resumption of Crude Oil Transportation in Southern Colombia and Increased Production in Argentina

Exploration and Development Operations Continue in Colombia, Argentina, and Peru

CALGARY, Alberta – January 12, 2009 – Gran Tierra Energy Inc. (NYSE Alternext: GTE; TSX:GTE), a company focused on oil exploration and production in South America, today announced that crude oil transportation has resumed in southern Colombia as a result of the lifting of the strike at the Orito facilities operated by Ecopetrol and gave an update on its exploration and production activities. With the resumption of crude oil transportation, Gran Tierra expects to attain its 15,000 barrels of oil per day (BOPD) net after royalty production target in the first quarter of 2009, and to continue growing production to 20,000 BOPD in the second half of 2009, while maintaining current gas production levels.

Production Update

In December 2008 Gran Tierra Energy produced approximately 2,250 BOPD net after royalty, down from a maximum of approximately 13,000 BOPD net after royalty attained in late November. In Colombia, December production averaged approximately 1,100 BOPD net after royalty and approximately 394 thousand standard cubic feet of gas per day (Mcf/day) net after royalty. In Argentina, Gran Tierra Energy production grew to an average of approximately 1,150 BOPD net after royalty in December. 

Colombia Operations Update

Chaza Block

Gran Tierra Energy recently conducted two short drill stem tests (DST) in Costayaco-6, the sixth well drilled in the Costayaco field that was discovered in 2007. DST-1 was conducted in the lower Villeta T sand over a four foot interval from 8,638 feet to 8,642 feet measured depth (MD). The test recovered approximately 151 barrels of formation water in 5.8 hours. DST-2 tested 22 feet over three upper Villeta T sand intervals including 8,594 – 8,602 feet, 8,612 – 8,616 feet, and 8,622 – 8,632 feet MD. The abbreviated test was inconclusive and only 20 barrels of water and a small amount of gas were recovered. Gran Tierra Energy plans to conduct additional testing operations in the upper Villeta T intervals in the first quarter of 2009 to confirm the presence or absence of oil that was indicated on logs and in cuttings. The next development well, Costayaco-7, is scheduled to be drilled in February. Gran Tierra Energy has a 100% working interest in the Chaza Block and is the operator.

Magangue Block

The installation of a booster compressor was completed in December for the Guepaje-1 production well. With the booster compressor, production has increased from approximately 500 Mcf/day to its current rate of approximately 3,200 Mcf/day gross, or approximately 1,000 Mcf/day net after royalty.   Gran Tierra Energy has a 37.8% working interest in the Magangue Block and is the operator.

Rio Magdalena Block

A service rig was moved to Popa-2, a gas-condensate discovery made in 2008, for an extended production test which is scheduled to begin in mid-February. Gran Tierra Energy also plans to commence a 70 square kilometer 3D seismic acquisition program over the Popa field and an adjacent prospect in the Rio Magdalena Block in the first quarter of 2009. Gran Tierra Energy has a 40% working interest in the Rio Magdalena Block and is the operator.

Guachiria Norte Block

An exploration well, Puinaves-2, is scheduled to spud in February 2009. Gran Tierra Energy has a 70% working interest and is the operator of the Guachiria Norte Block.

Guachiria Sur Block

A 115 square kilometer 3D seismic program is currently being acquired in this block to define future drilling prospects. Gran Tierra Energy has a 70% working interest and is operator of the Guachiria Sur Block. 

San Pablo Block

Planning continues for an exploration well in the second quarter of 2009. Gran Tierra Energy has a 100% working interest in the San Pablo Block and is the operator.

Argentina Operations Update

Ipaguazu Block

Gran Tierra Energy completed a successful re-entry at IP.x-1, a previously suspended oil well, achieving an average flow rate of 220 BOPD through a 1.97″ choke. Gran Tierra Energy plans to install a production facility at Ipaguazu and place IP.x-1 on production in the second quarter of 2009. Gran Tierra Energy has a 100% working interest in the Ipaguazu Block and is the operator.

Valle Morado Block

A re-entry was conducted at VM.x-1001, a previously suspended gas well, achieving an average flow rate of 4,940 Mcf/day along with 3,271 barrels of water per day.   The data collected is currently under review to determine the feasibility for further development.

Surubi Block

A successful workover was conducted at Proa-1, the oil field discovery well drilled in 2008, to eliminate water channeling from an upper interval. After the workover Proa-1 has an average production rate of 918 BOPD gross with a 7% watercut. Gran Tierra Energy has an 85% working interest and is the operator of the Surubi Block.

Peru Operations Update

Blocks 122 and 128

Gran Tierra Energy is proceeding with permitting and planning for the acquisition of 500 kilometers of 2D seismic data, which is scheduled to begin in the fourth quarter of 2009. Gran Tierra Energy has 100% working interest in Blocks 122 and 128 and is the operator.

About Gran Tierra Energy Inc.

Gran Tierra Energy is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada and incorporated in the United States. The company holds interests in producing and prospective properties in Colombia, Argentina and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Gran Tierra Energy trades on the NYSE Alternext under the symbol “GTE” and on the Toronto Stock Exchange under the symbol “GTE”.

Additional information concerning Gran Tierra Energy is available at www.grantierra.com , on SEDAR (www.sedar.com) and with the Securities and Exchange Commission (www.sec.gov).

Forward Looking Statements

The statements in this press release regarding Gran Tierra Energy’s expectations regarding first quarter and future oil production rates and gas production levels, and plans and schedules for testing, drilling and seismic acquisition, and plans to install a production facility at Ipaguazu, are “forward-looking statements” within the meaning of the U.S. federal and Canadian securities laws, including Canadian Securities Administrators’ National Instrument 51-102 Continuous Disclosure Obligations and the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results or outcomes to differ materially from those contemplated by the forward-looking statements. Although, Gran Tierra Energy believes that the assumptions underlying, and expectations reflected in, these forward-looking statements are reasonable, it can give no assurance that these assumptions and expectations will prove to be correct.

Factors that could cause results to differ materially from those described in the forward-looking statements include: Gran Tierra Energy’s operations are located in South America, and unexpected problems can arise due to additional strikes, guerilla activity, technical difficulties, operational difficulties and weather conditions which impact operations, including the exploration, production, transportation or sale of oil and gas; heightened unrest in Colombia could imperil the safety and security of Gran Tierra Energy’s assets and personnel despite the safety measures Gran Tierra Energy has put in place to address the current situation, which could also delay the testing and drilling and could also impact production; and those other risks found in the periodic reports filed by Gran Tierra Energy with the United States Securities and Exchange Commission, including in the section entitled “Risk Factors” in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 6, 2008, and available at the Securities and Exchange Commission’s internet site www.sec.gov and on SEDAR at www.sedar.com.

All forward-looking statements in this press release are expressly qualified by information contained in each company’s filings with regulatory authorities and, subject to its obligations under applicable securities laws, Gran Tierra Energy does not undertake to publicly update forward-looking statements, whether as a result of new information, future events or otherwise.