Russian President Vladimir Putin said a friend of his named in the so-called Panama Papers leaks had done nothing wrong and had spent the money he rightfully earned buying expensive musical instruments to be donated to public institutions.

Media reports based on the leaked documents from a Panama­-based law firm have alleged that Sergei Roldugin, a concert cellist and personal friend of Putin, had quietly built up a sprawling business empire involved in offshore transactions that might be linked to the Russian leader.

Speaking to supporters in St. Petersburg, Putin said the leaks were part of an orchestrated attempt to destabilize Russia by fabricating allegations of corruption.

"Our opponents are above all concerned by the unity and consolidation of the Russian nation. They are attempting to rock us from within, to make us more pliant," said Putin, in his first public comment on the leaks.

"There is a certain friend of the president of Russia, he did such and such a thing, and there is probably a corruption element there," Putin said, describing the allegations. "But there isn't any [element of corruption]."

Putin said Roldugin is a brilliant musician and a minority shareholder in a Russian company from which he earned some money, but not "billions of dollars."

He asserted that Roldugin had spent almost all the money he made from the venture named in the leaks on the acquisition of expensive musical instruments abroad, instruments which he was in the process of handing over to state institutions. "I am proud to have such a friend," said Putin.

"WikiLeaks has now shown us the fact that officials and official organs of the United States stand behind this," Putin added, referring to WikiLeaks' post on Twitter on Wednesday, which said, "US govt funded #PanamaPapers attack story on Putin via USAID."

The papers, which included more than 11.5 million documents from Panamanian law firm Mossack Fonseca containing details about clients around the world, were leaked to the German newspaper ­Sueddeutsche Zeitung.

They then became part of a broader investigation coordinated by the International Consortium of Investigative Journalists.

The files prompted Sigmundur David Gunnlaugsson, the prime minister of Iceland, to resign, put British Prime Minister David Cameron under pressure over his family's financial affairs, and sparked calls in Ukraine to investigate President Petro Poroshenko.

Dmitry Peskov, Putin's spokesperson, has dismissed allegations against the Russian president as the result of "Putinophobia" and said that the journalistic consortium behind the Panama Papers included "many former [US] State Department and CIA employees, as well as those of other intelligence services."