"We have information that, once again, this was done on the recommendation of the US State Department," Putin said on Monday at a meeting with activists of his United Russia party, referring to a pull-out decision earlier this month by an election monitoring group.

The Office for Democratic Institutions and Human Rights (ODIHR), a Warsaw-based branch of the Organization for Security and Cooperation in Europe (OSCE) that had been planning to send observers to Russia in the month prior to the elections, refuted Putin's claim.

The cancellation had to do with problems obtaining visas, OSCE Director Christian Strohal said in an interview with Reuters news agency.

"It's unfortunate that we didn't have any other choice," Strohal said. "This sort of thing has never happened to us before."

Putin also said the pull-out would put a damper on Russian-US relations and that any criticism from Washington regarding Sunday's vote would further strain ties.

"We will take this into account in our inter-state relations," said Putin, suggesting a cool-down in US-Russian dealings.

EU leader condemns police crackdown

A police crackdown on opposition demonstrators over the weekend fuelled criticism that the parliamentary elections are being staged to ensure a hefty majority for United Russia.

Opinion polls suggest that United Russia, with Putin at the helm, is expected to take the election with a 60 percent majority or more.

European Commission President Jose Manuel Barroso expressed concern on Monday about the severity of the suppression of the weekend demonstration, where truncheon-armed police officers arrested an estimated 200 people.

"The right to peaceful free speech and assembly are basic fundamental human rights and I very much regret that the authorities found it necessary to take such heavy-handed action," said Barroso in a statement.

Putin's second term ends soon

Russia's constitution stipulates a maximum of two terms for heads of state, which means Putin is required to leave office next year.

Some observers have speculated, however, that Putin may step down now and run again in the presidential elections planned for March 2, 2008, in order to get around the two-term limit, reported Reuters. In any case, the president has indicated that he would maintain political influence after stepping down.

Putin's wide popularity at home stems largely from his image as a bearer of stability following the tumultuous post-Soviet era under his predecessor, Boris Yeltsin.