Documents claiming to prove that the former Russian president, Boris Yeltsin, opened a Swiss bank account in 1995 are false, according to the Russian prosecutor's office.
The Russian state media reported that the documents were reproduced by a Russian weekly publication one year ago.
"The copies of the documents that allegedly carried the signature of Yeltsin and (the former financial chief, Pavel) Borodin have been acknowledged as false," said Ruslan Tamaiev, head of the inquiry opened by the prosecutor's office.
He said that the Swiss justice system had also informed him that no account in the name of Boris Yeltsin had been opened at the Banco del Gottardo.
Tamaiev said that he has not questioned Yeltsin about the affair, because he is "convinced that he is not involved in the corruption case that the press has talked about."
The Russian prosecutor's office said it was due "to take a decision" bearing in mind these new developments.
A Lugano-based construction company, Mabetex, allegedly paid kickbacks to senior Russian officials in return for lucrative contracts to refurbish buildings in Moscow owned by the Kremlin.
The Swiss authorities have reportedly asked Russia to hand over documents relating to the corruption inquiry and issued an international warrant for Borodin's arrest.
A similar case, involving another Ticino-based company, Mercata, is also being investigated. The company is alleged to have given bribes worth $60 million.
swissinfo with agencies