Switzerland said Tuesday it had rejected a request from Russia to extradite a Russian businessman, who is already fighting an extradition to the United States over suspicions of large-scale insider trading.

The Swiss justice ministry confirmed Swiss media reports that it had recently rejected a Russian request to extradite Vladislav Klyushin.

In an email to AFP, a ministry spokeswoman explained that "the facts described in the request are not punishable under Swiss law," adding that it had informed Russian authorities on August 12 that "the request had been rejected".

Klyushin, who stands accused of "insider trading in the tens of millions of dollars together with several accomplices", was arrested in the Swiss canton of Wallis in March.

According to Russian opposition media, the businessman was very close to senior Kremlin official Alexey Gromov.

He reportedly heads several companies, including the M13 group which specialises in IT solutions for media monitoring and cyber-security consulting.

The justice ministry said it had received an extradition request from Russia on April 7.

That was followed by a US request on April 19, "based on the bilateral extradition treaty between Switzerland and the United States."

Bern agreed to the US request on June 24, despite protests from Klyushin, who has appealed the decision to Switzerland's highest court.