Swiss authorities have ordered the release of more than 50 paintings belonging to the Pushkin state art museum in Moscow.
Edouard Manet's Bouchon was among the works in the exhibition
The works - part of a collection on loan to an exhibition - were seized by police on behalf of a local firm which claims Russia owes it money.
But to avoid upsetting ties with Moscow, the Swiss government ordered the immediate released of the works.
Among the collection were pieces by Manet, Renoir, Picasso and Matisse.
The Pierre Gianadda Foundation display at Martigny was said to have been insured for $1bn (£597m).
The company, Noga, said it was owed money for food deliveries in the 1990s.
It has sought the seizure of various Russian assets abroad since 1997 as part of the long-running legal battle.
The paintings had been loaned to Switzerland for five months by Moscow's renowned Pushkin museum.
But just as they were about to be returned to Russia, they were seized by Swiss police.
The BBC's Imogen Foulkes in Bern says the seizure of the paintings caused real anger in Moscow and threatened to destroy all cultural ties between the two countries.
Other Russian galleries were already ordering their works on loan to Switzerland to be withdrawn.
Pushkin director Irina Antonova said it was unacceptable that works of art should become "hostages" in political disputes.
So the Swiss government soon stepped in to say the paintings should be returned because international law barred the seizure of cultural goods for private reasons, said foreign ministry official Paul Seger.
Our correspondent says it is the latest in a series of increasingly bizarre attempts by Noga. It has in the past tried, unsuccessfully, to seize other Russian property, including two aircraft at the Paris air show and even a yacht.