A leading international election monitoring group sent an advance team to Russia on Wednesday, despite complaints that restrictions from Moscow would make it difficult to conduct an observation mission for the country's presidential election next month.

A four-member team from the election monitoring arm of the Organization for Security and Cooperation in Europe was slated to arrive in Moscow on Wednesday, said Curtis Budden, spokesman for the Warsaw-based Office for Democratic Institutions and Human Rights.

One more person will join the team Thursday, Budden said.

But there remain several sticking points between the group and the Kremlin over how an observation would proceed - including when it would start, Budden said.

"These conditions certainly aren't ideal for observations and what we've outlined are minimal, minimal requirements for any sort of effective observation given the restrictive circumstances that we're allowed to operate in," Budden said.

"The fact that there are limitations at all is already completely going against existing practice," he added. "Russia is the only country that is doing this."

Following the initial team, 15 additional observers have applied for visas and plan to travel to Russia on Friday to help prepare for a possible full-scale monitoring mission, Budden said.

"In the meantime, we hope we will get a response from Moscow on the question of when the (rest of the) observers can arrive," Budden said.

Budden stressed that his office continues to insist the 70-member observer mission _ pared back from some 400 four years ago - be on the ground by Feb. 15, while Russia has proposed Feb. 20. The voting takes place March 2.

Russia's Foreign Ministry criticized the organization's tack, adding that Moscow is acting "in strict compliance" with international electoral obligations

"The unpreparedness of the ODIHR to cooperate with Russia ... once more gives evidence of the necessity of fundamental reform of this institution of the OSCE," the ministry said in a statement.

Russian news agencies quoted Deputy Foreign Minister Andrei Denisov as saying Moscow regrets ODIHR's rejection of the Russian offer to start the mission in full on Feb. 20 and hopes for further talks on the issue.

"One can only express regret. We hope that the negotiations will be continued," ITAR-Tass quoted Denisov as saying.

Monitors from the group skipped Russia's Dec. 2 parliamentary elections, saying Russia granted them insufficient time to conduct a satisfactory monitoring operation.

In the eyes of Western governments and Kremlin critics in Russia, a boycott by the organization would underscore doubts about the legitimacy of a vote whose result is seen as all but a foregone conclusion.

Liberal opposition leaders have accused the Kremlin of keeping them off the ballot for the election, which is almost certain to be won by Putin's favored successor, Dmitry Medvedev, who has said he will name Putin as his prime minister if elected.