The source was confirming a remark made earlier in the day by Britain's trade, investment and foreign affairs minister, Mike O'Brien, who told a London conference that Siemens had just been awarded a major contract in Iraq.
"Siemens won a contract to build a gas turbine...," the industry source said, adding the work was being sub-contracted by US engineering and construction giant Bechtel.
The turbine has a generation capacity of 266 megawatts of power, the source said.
San Francisco-based Bechtel is the lead contractor for the US Agency for International Development and has so far racked up over $1 billion in work to rebuild the country's schools, bridges, and power and water infrastructure.
The industry source also said Siemens had already won subcontracts worth about $50 million in Iraq.
A spokeswoman for Siemens UK said in London that the company was in talks with Bechtel but added: "As yet there is no formal contract in place." She gave no more details.
On Wednesday, Washington pledged open and fair competition for at least 25 new Iraq contracts worth up to $18.7 billion, and said bidding would be open to firms from the United States, Iraq and from countries that participated in the war effort.
Germany was one of the most vociferous opponents in Europe of the war in Iraq. It teamed with France and Russia in opposing the US-led invasion on Iraq.
The invading forces destroyed much of Iraq's infrastructure including electricity and water supply. Since then, among other things, power shortage has been one of the major problems Iraqis have to contend with.