Switzerland is likely to come under pressure to allow the release of former Kremlin aide, Pavel Borodin, when the Russian foreign minister, Igor Ivanov, holds talks with Swiss ministers in Bern on Thursday.
But the Geneva prosecutor handling the case, Bernard Bertossa, says he is confident Borodin will still be extradited to Switzerland.
Borodin was arrested in New York on January 17 under an international arrest warrant issue by magistrates in Geneva. He is accused of laundering $25 million (SFr41 million) allegedly received from two Swiss firms in return for lucrative contracts to renovate the Kremlin.
Borodin, who had travelled to the United States for President George W Bush's inauguration, has been denied bail.
Russia has strongly protested against the arrest, and warned that it could lead to a major international and diplomatic scandal. The Russians insist that because the alleged offences took place in Moscow, only a Russian prosecutor can successfully pursue the case.
During his one-day visit, Ivanov will hold talks in Bern with the Swiss president, Moritz Leuenberger, and the foreign minister, Joseph Deiss. The Swiss foreign ministry says no other talks have been scheduled for Ivanov.
The Russian minister is expected to ask the Swiss authorities to persuade Bertossa to drop the case against Borodin, or allow him to be released on bail.
"I've no idea what Mr Ivanov will say. But in our country, the independence of the judiciary is respected. So I do not think there will be any kind of interference," Bertossa told swissinfo.
"In a democratic country, diplomatic pressure cannot be used on the judiciary to allow different treatment for such-and-such a person. The only thing we can do is follow the correct legal procedures," the magistrate said.
Russian prosecutors dropped their case in December after they said their investigation had uncovered no evidence of wrongdoing.
Critics said the case was dropped because of Borodin's continuing close links with the Russian authorities. The Geneva prosecutors believe they have more than enough evidence to have the Russian extradited.
"I have no reason not be confident that Mr Borodin will be extradited," Bertossa told swissinfo.
"We have always had good experiences with the United States, which usually respects extradition conventions. We have no reason to believe they will not do so in this case," he said.
The extradition request is currently being drawn up by the Geneva prosecutor's office and the Federal Police Office. It is expected to be submitted to the US justice authorities by the end of February.
Bertossa has already turned down a deal offered by Russia, under which it would guarantee that Borodin gave evidence at the appointed time.
"If Mr Borodin wants to be heard by the Swiss magistrates, he has to accept his extradition," Bertossa said.
"There is no legal provision for the Russian authorities to guarantee his presence. We cannot accept such a proposition," he added.
Borodin, who currently holds the largely ceremonial post of State Secretary of the Russian-Belarussian Union, was the Kremlin property manager under former President Boris Yeltsin.
He is accused of taking several million dollars' worth of bribes from Mabetex and Mercata, two companies based in the Swiss canton of Ticino, which had contracts to renovate Kremlin buildings and the presidential plane. Some of the money was allegedly laundered through Swiss accounts held by Borodin.
Two of Yeltsin's daughters were also implicated in the scandal.
by Roy Probert