The artworks, which were on loan to the Swiss-based Pierre Gianadda Foundation, were seized on behalf of the Swiss firm Noga, which is claiming unpaid debts by Russia in a long-running legal battle.
Russian embassy official Igor Petrov said the 25 paintings were seized last weekend. They are worth a total of about one billion dollars, Petrov told AFP.
The Swiss foreign ministry confirmed the seizure and was due to issue a statement later.
The paintings were part of a five-month exhibition of French art from the the Pushkin collection at the foundation which ended on Nov. 13.
Petrov said Swiss authorities stopped six vehicles which were transporting the artworks. Three were under seizure in Basel, on the border with Germany, two in Martigny and one in Geneva, he said.
It was not clear which paintings had been seized.
The Martigny exhibition included 55 artworks, including major paintings byEdouard Manet">Manet, Claude Monet">Monet, Renoir, Edgar Degas">Degas, Van Gogh, Paul Gauguin">Gauguin, Paul Cezanne">Cezanne andAndre Derain">Derain.
The Pushkin Museum's renowed French collection comprises more than 700 artworks.
Reacting to the news, the lead item on all Russian television news bulletins on Wednesday, Russian parliament speaker Boris Gryzlov said in Moscow: "The art masterpieces of the world cannot be taken hostage for legal disputes," the ITAR-TASS news agency reported.
"It's really scandalous," said the former interior minister, appealing for respect of "international law."
The federal cultural and cinematography agency meanwhile froze all ongoing negotiations for loans of artwork to Swiss galleries, calling the seizure a "gross violation of international legislation on the protection of cultural property."
Noga's dispute with Russia dates back to the 1990s, and has its roots in a $1.5 billion deal to swap oil for food.
Russia halted its oil deliveries, and Noga has been trying to get back the money it says it is owed by Moscow.
In 1997, Swedish courts ordered Russia to pay Noga $27 million. In its effort to force Russia to pay up, Noga has sought to obtain the seizure of Russian assets abroad.
Five years ago, French authorities seized the Sedov, a Russian sail-training ship that was taking part in a boat festival in France, on behalf of the company. The ship was released after a week.
In June 2001, Noga tried to get the French to seize two Russian planes at the Paris air show, but the aircraft left France the same day.
Copyright 2005 Agence France-Presse