Russia’s second-largest oil firm, LUKOIL, has suspended work on the Anaran oil project in Iran that it is developing with Norway’s Norsk Hydro due to U.S. sanctions, Interfax news agency reported on Monday.

Interfax quoted LUKOIL Vice-President Leonid Fedun as saying the LUKOIL-Hydro joint venture had to suspend work on the project in western Iran.

The Azar field in the Anaran block was discovered in the summer of 2005. It is believed to contain two billion barrels of oil. The agreement on the exploration of the Anaran block was signed by the National Iranian Oil Company and Hydro in 2000. LUKoil joined the project in 2003.