The Federal Security Service, or FSB, the leading successor of the Soviet KGB, said yesterday it checked the institutions and found no evidence to support US claims that they had provided weapons technology to Iran.

The agency said in a statement that the US move was the result of ``misunderstanding, or, probably, oversight of the American secret services.''

Prime Minister Yevgeny Primakov and other senior Russian officials have denied Iran received any such technology from Russia and harshly criticised the Americans for placing sanctions on the three institutions, warning that the move could damage US-Russian relations.

The Americans fired back, accusing the Kremlin of ignoring the problem. The United States also threatened to cut back or even eliminate American satellite launches in Russia.

Russia receivestens of millions of dollars for each of these launches.

At the end of this year, Washington ``will take into account very seriously progress, if any, that we have made in getting Russia to stop its entities from supporting Iran's missile program,'' State Department spokesman James P Rubin said on Wednesday.

The Russian government insisted yesterday that the nation's space companies were not involved in any dubious cooperation with Iran, and suggested the US pressure was reminiscent of the indirect efforts at affecting policy common during the Cold War.

Foreign Minister Igor Ivanov said yesterday the United States was reverting to ``outdated instruments.''

``These are the instruments of a past time, from which we are trying to break,'' Ivanov was quoted by the Interfax news agency as saying.

Foreign ministry spokesman Vladimir Rakhmanin said that tying the allegations to satellite launches was ``arbitrary.''

``The cessation of (space) cooperation would be bad not only for Russian companies -- andof course it would be very bad for Russia companies -- but it would be bad for American companies involved in this cooperation,'' Rakhmanin added.

President Boris Yeltsin's administration said the president has ordered the National Security Council to investigate and the Kremlin might take unspecified retaliatory actions.

``I don't exclude that it would be rather harsh,'' Yeltsin spokesman Dmitry Yakushkin said on Echo Moscow radio.

The US sanctions announced earlier this week barred the D Mendeleyev University of Chemical Technology, the Scientific Research and Design Institute of Power Technology and the Moscow Aviation Institute from purchasing US-made goods or exporting products to the United States.

Overall, the United States has introduced sanctions against 12 Russian organisations for allegedly sending sensitive technologies to Iran. The US government has not offered evidence to support its claims.

Iran is building a nuclear power plant with Russian help, but says it is not seeking to buildnuclear bombs or other weapons of mass destruction.

``Russia cannot be suicidal here,'' Yakushkin said. ``If the matter is about Iran, it is our neighbour, and we cannot export something there that could later become a threat to ourselves.''

Some Russian politicians said that the Russian government should take the American accusations more seriously.

Alexei Yablokov, a prominent Russian anti-nuclear campaigner and former Yeltsin advisor, noted that the government has acknowledged previous Iranian attempts to procure Russian weapons technology.

Vladimir Lukin, a liberal lawmaker who heads parliament's international affairs committee, said, ``Russia must make a clear choice between dealing with Iran... or developing technological cooperation with the West,'' according to the Itar-Tass news agency.