The Swiss authorities have delayed extraditing Russian former nuclear energy minister Yevgeny Adamov to the United States where he faces fraud charges.
The Federal Justice Office said on Thursday Adamov's lawyers had informed them that he would appeal against the extradition order.
"They have informed us in writing... So we cannot extradite Mr Adamov immediately," said the Justice Office's Rudolf Wyss.
Lawyers for Adamov had five days in which to tell the Swiss authorities of their intention to appeal against Monday's extradition order before it came into force.
Adamov now has a further 25 days to formally lodge an appeal with the Federal Court against his deportation.
Russia, which is also seeking Adamov's extradition, has condemned the Swiss decision to comply with the US request.
On Wednesday evening the Russian foreign ministry summoned the number two at the Swiss embassy in Moscow and expressed "surprise and displeasure" at the move, the Swiss foreign ministry said.
Switzerland said on Monday that it had given precedence to the US request because "had priority been given to Russia, Adamov's Russian citizenship would have meant that he could not subsequently have been extradited forward" to the US.
Swiss authorities arrested the former minister on a US warrant on May 2, while he was visiting his daughter in Bern.
A US federal grand jury in Pittsburgh, Pennsylvania, has since indicted the Russian on charges of conspiracy to transfer stolen money and securities, conspiracy to defraud the US, money laundering and tax evasion.
US authorities suspect Adamov of embezzling energy department funds and diverting them into private projects in the US, Ukraine and Russia.
In its own extradition demand, Moscow accused Adamov of fraud between 1998 and 2001 during his term of office.
The ex-minister has not denied he put money into private accounts but has said this was normal practice in Russia to shield money from hyperinflation, an unstable banking system and corruption rife after the collapse of communism.
swissinfo with agencies
Yevgeny Adamov was Russia's atomic-energy minister from 1998 to 2001, when a parliamentary commission accused him of corruption.
He is charged by the US with embezzling funds that had been destined for nuclear-safety upgrades in Russia.
Russia had presented a formal extradition request to the Swiss authorities on May 17, accusing Adamov of fraud.