The Swiss foreign minister, Joseph Deiss, has told his Russian counterpart that the government can do nothing to secure or speed up the release of a former Kremlin aide, Pavel Borodin, who Swiss prosecutors accuse of money laundering.
Speaking in Bern late on Thursday, Deiss told Igor Ivanov that the case was a "legal matter and not a political affair", and that the government's hands were tied by Swiss law which prevents any political interference in judicial matters.
His comments came in response to Ivanov's request that Switzerland bring the matter to a close as soon as possible. "Moscow hopes that Switzerland will quickly take steps in the Borodin case so a solution can be found," said Ivanov.
He justified Russia's intervention in the case, saying that "all civilised and democratic states must defend the rights of their citizens".
Borodin is being held without bail in New York, where he is awaiting extradition to Switzerland. He was arrested on January 17 at the airport by police acting on an international warrant issued by magistrates in Geneva.
They accuse Borodin of laundering $25 million (SFr41 million), which he allegedly received from two Swiss firms in return for granting lucrative contracts to renovate the Kremlin.
Borodin denies any wrongdoing, as have the two Swiss firms - Mabatex and Mercata - which are implicated in the case.
Russia last year closed its investigation into the case, saying there was not enough evidence to proceed. That decision was criticised at the time as being politically motivated.
Overall, Deiss described relations with Russia as excellent. He also disclosed that the Russian President, Vladimir Putin, had been invited for an official visit to Switzerland.
The visit has been scheduled for the second half of this year.
swissinfo with agencies