British-American financier Bill Browder says he has been released by Spanish police after being briefly detained on a Russian Interpol arrest warrant.
Browder, the founder of Hermitage Capital Management, wrote in a tweet that he was released after Interpol's general secretary in Lyon, France, had instructed Spanish police not to honor Russia's arrest request.
Browder said he had flown to Spain to give evidence to "Spanish anti-Russia mafia prosecutor Jose Grinda about the huge amount of money from the Magnitsky case that flowed to Spain."
A Spanish national police spokeswoman said Browder had been detained in Madrid and taken to a police station to check on the Interpol warrant but that it was found to be no longer valid.
But Browder later said on Twitter that the information provided by the Spanish national police spokeswoman about the warrant was incorrect.
"Just to be clear, my arrest this morning in Madrid was the result of a SIXTH Russian arrest warrant using Interpol channels," Browder said. "It was NOT an expired warrant, but a live one. Interpol is incapable of stopping Russian abuse of their systems."
Browder has led a global push for sanctions against Russian officials implicated in the death of imprisoned Russian whistle-blower Sergei Magnitsky.
The latest tweets come just a few hours after Browder had said on Twitter that he had been arrested and was being taken to a police station.
Browder was found guilty in absentia by a Moscow court in December of large-scale tax evasion of some 3 billion rubles ($48 million) and sentenced to nine years in prison.
He was also fined 200,000 rubles (about $3,500) and banned from conducting business activities in Russia for three years.
His lawyers have appealed the verdict.
Ivan Cherkasov, Browder's co-defendant, was also given an eight-year sentence in absentia.
Browder and Cherkasov live in Britain.
Browder has repeatedly dismissed allegations against him as baseless, politically motivated, and revenge for his work to encourage countries to pass legislation similar to the U.S. Magnitsky Act, a 2012 law that imposed visa bans and asset freezes on Russians alleged to be involved in the death of whistle-blowing accountant Magnitsky.
At least five other countries have since implemented sanctions based on the Magnitsky Act.
In December, Browder called for Interpol to "suspend Russia’s membership for flagrant abuse of the Interpol system."