BEIJING/LONDON (Reuters) - China's top oil and gas company CNPC is considering taking over Total's TOTF.PA stake in a giant Iranian gas project if the French company leaves Iran to comply with any new U.S. sanctions, industry sources said.

FILE PHOTO: The logo of CNPC (China National Petroleum Corporation) is pictured at the 26th World Gas Conference in Paris, France, June 2, 2015. REUTERS/Benoit Tessier/File Photo

Total signed the $1 billion deal to develop the South Pars gas field in July. The contract gave CNPC the option to take over Total’s stake if it pulled out, according to sources involved in the talks.

The deal was the first major Western energy investment in the Islamic Republic since international sanctions, including most of those imposed by the United States, were lifted as part of a landmark agreement in 2015 over Iran’s nuclear program.

But after U.S. President Donald Trump refused in October to certify that Tehran is complying with the deal, Congress will have to vote on whether to reimpose sanctions on Iran.

It was unclear when a vote would take place or what sanctions might be imposed, but they could bar companies working in Iran from also operating in the United States.

Total has much larger operations in the United States and Chief Executive Patrick Pouyanne said it would leave if it were no longer able to operate in Iran.

Under the terms of the agreement to develop phase 11 of South Pars, the world’s largest gas field, CNPC could take over Total’s 50.1 percent stake and become operator of the project if Total is forced to withdraw from Iran, a senior Beijing-based source with knowledge of the joint-venture agreement said.

CNPC has a 30 percent stake, while the Iranian national oil company’s subsidiary PetroPars holds the remaining 19.9 percent.

CNPC officials have held internal talks in recent weeks to discuss the implications of taking control, according to three industry sources briefed on the talks.

Spokespeople for CNPC, Total and Iran’s National Oil Company (NIOC) declined to comment.

A senior official at Total said the company has “some mechanism that permits us to exit the deal softly if forced to by international sanctions.”

Any change would likely delay the project’s timetable as Total is already in discussion with service companies and is expected to award contracts early next year, the sources said.

SMALL LOSS

A change in ownership structure would mean that CNPC would shoulder 80 percent of the cost of the project, estimated at $2 billion for the first stage.

It would also have to bring in new technical teams to manage and operate the offshore project. This could mean involving its rival CNOOC 0883.HK, China's largest offshore operator.

“In the case of a Total withdrawal, CNPC may need to bring in CNOOC because CNPC has little experience offshore,” a second senior Chinese industry official said.

Total might still be able to operate in Iran depending on how the U.S. sanctions are worded, and because the European Union, China and Russia are expected to stick to the nuclear deal, Pouyanne said in October.

Pouyanne has also raised the possibility of France getting a waiver from the United States to operate in Iran, similar to one it had obtained in the late 1990s.

“If we can legally execute the contract, we will execute the contract,” he said in a speech at the Oil & Money conference.

Total faces losses of several tens of millions of dollars if it pulls out of the project, but that is a relatively small sum for the 120 billion euro company, the Total source said.

The French company last month opened an office in Washington in a bid to strengthen relations with the U.S. administration as it prepares to invest billions in Iran.

The South Pars project will have a production capacity of 2 billion cubic feet per day, or 400,000 barrels of oil equivalent per day including condensate, Total has said. It would start supplying the Iranian domestic market starting in 2021.

Iran is the third largest producer in the Organization of the Petroleum Exporting Countries and the Total deal was a breakthrough in efforts to revive its economy following the removal of international sanctions.