MOSCOW/PANAMA CITY - Russian President Vladimir Putin on Thursday acknowledged the accuracy of the Panama Papers revelations, but claimed funds had been spent on musical instruments as he blamed the leak on the United States.

The Papers revealed that Putin's associates, notably cellist Sergei Roldugin, "secretly shuffled as much as $2 billion through banks and shadow companies," according to the International Consortium of Investigative Journalists (ICIJ).

During Putin's annual phone-in with the nation, a male caller asked the president why he did not react to "slander in Western media and "unreliable information about offshores."

Putin sighed, saying that "strange as it may seem, they are not publishing unreliable information about offshores. The information is accurate."

"I get the impression it (the report) was put together not even by journalists but most likely by lawyers," Putin said of the leaked information. "They do not specifically accuse anyone of anything."

The leaks "just serve to muddy the waters" by raising the possibility that "money from these offshores goes to some officials, including to the president," Putin said. Those who investigated the Panama papers were "wide of the mark," he insisted.

He alleged that "staff of US official institutions" were working on the disclosures, which he called "acts of provocation" ahead of Russia's parliamentary elections in September. "We should not expect any repentance from them, they will keep doing it anyway and the closer the elections, the more smear campaigns there will be," Putin said.

In patriotic rhetoric, Putin boasted that Russia "cannot be manipulated" and must be "spoken to with respect."

He reiterated his defence of his cellist friend, insisting Roldugin spends all his money on costly musical instruments and is not corrupt. "In Russia you can just about imagine a bribe paid in Borzoi puppies, but in violins and cellos? That's a new one to me," Putin said.

Roldugin has now spent all his money on instruments and is in debt, Putin added. "Sergei Pavlovich has nothing left because he has spent more money on those instruments than he had," Putin said, using a respectful patronymic.

Roldugin bought two cellos and two violins, Putin said. "The last one he bought ... cost around $12 million," Putin said, calling it a Stradivarius cello known as Stuart from 1732.

Meanwhile, Panama's public prosecutor against organized crime said Wednesday there was no evidence so far to take action against the law firm at the center of the Panama Papers scandal, following a raid lasting 27 hours on its offices.

"Right now we don't have any strong evidence allowing us to take any sort of decision" against the firm Mossack Fonseca, the prosecutor, Javier Caraballo, told reporters. He said the swoop on its law offices, located in Panama's banking district, had begun on Tuesday on the basis of the news reports about the offshore businesses it created and in some cases ran for wealthy clients around the world.

"The information we have collected is what will permit us to have evidence to take a decision later on," Caraballo said.

He said the investigation was complicated by the fact that the firm kept most of its records in digital form, on more than 100 computer servers, and not on paper.

But he added that the firm had "cooperated" with his investigators.

Nearly 40 years' worth of archives from Mossack Fonseca have been pored over by hundreds of journalists around the world since being given to a German reporter a year ago. They have resulted in the so-called Panama Papers : a series of reports exposing politicians, celebrities and some criminals who used Mossack Fonseca's services to stash assets in offshore companies.

Mossack Fonseca's founders, lawyers Ramon Fonseca and Juergen Mossack, insist they did nothing illegal.

They stress that offshore companies in themselves are not illicit - and they were not responsible for any activities their clients did with the entities.

Fonseca is a friend to Panama's President Juan Carlos Varela and, until March, served as a senior advisor on his cabinet.

The Panama Papers revelations have triggered a multitude of probes around the world as authorities look for evidence people named in them might have committed tax fraud, money laundering or other criminal acts.

Varela's government is currently fighting to prevent other countries responding to the scandal by putting Panama back on international blacklists of nations that facilitate money laundering or tax evasion.

Panama's chief state prosecutor, Kenia Porcell, earlier Wednesday gave a news conference in which he noted that "in Panama, tax evasion does not constitute a crime."

He said, however, that the country was extending "all necessary cooperation" to address the scandal.

Porcell said he had been contacted by counterparts from Peru, Venezuela, Guatemala, El Salvador and Costa Rica, but did not elaborate.