Russia's gas giant Gazprom CEO, Alexei Miller (R), Russian President Vladimir Putin (2nd L) and Vice Premier of the People's Republic of China Zhang Gaoli (L) on September 1, 2014. ALEXEY NIKOLSKY/AFP/Getty Images

Two former U.S. senators -- Republican Majority Leader Trent Lott and Democrat John Breaux -- are now working as lobbyists for the Russian-owned Gazprombank, according to a Friday filing. That bank, controlled by the Russian state-owned Gazprom energy company, was a target of U.S. sanctions in July.

The filing, first spotted by the Center for Public Integrity, a non-profit investigative journalism organization, lists the two former senators as lobbyists on behalf of the institution for "banking laws and regulations including applicable sanctions." They're representing the Russian bank through the lobbying firm, Squire Patton Boggs. (The pair started working for Patton Boggs when it bought their shop --  Breaux-Lott Leadership Group -- four years ago. Lott left the Senate in 2007, while Breaux left in 2005.)

Since then, Lott and Breaux have become experienced lobbyists to their former colleagues in Congress. Earlier this year, the pair worked with former Democratic Senator Tom Daschle to lobby on behalf of the tele-health industry. They also lobbied on behalf of AT&T during its proposed merger with T-Mobile.

Along with Rosselkhozbank, Gazprombank was one of two major Russian financial institutions in the country to ask for government aid following Western sanctions. The sanctions were imposed as a punishment for Russia's role in the Ukraine crisis.

In the second half of 2013, Gazprom paid another lobbying firm, Ketchum, about $3.7 million dollars in fees, according to filings compiled by ProPublica. Ketchum took in about $17 million in fees between 2006 and 2012 from the same account. Ketchum also has a history of lobbying for the Russian government in the U.S..