The Kremlin on Tuesday branded U.S. sanctions against two leading Russian arms exporters "an unfriendly act" and warned they could rebound on U.S.-Russia relations. The United States announced sanctions on Friday on seven firms from Russia, India, North Korea and Cuba for selling restricted items to Iran, which Washington fears is trying to make nuclear weapons. The sanctions were imposed on Russian state export agency Rosoboronexport -- and state-owned warplane maker Sukhoi. "This looks like unfair competition. It was an unfriendly act towards Russia and it was not done in a spirit of cooperation," Kremlin spokesman Dmitry Peskov said. "If we are to speak about possible consequences of this act for bilateral relations, of course it has not contributed to a further strengthening of the partnership. Among other things we can not rule out further negative consequences for this relationship," he said. The U.S. State Department said it imposed the sanctions after Washington received information the companies had transferred materials to Iran that could contribute to the development of weapons of mass destruction or missiles. The sanctions took effect on July 28 and will be in place at least until July 28, 2008, Reuters reported.