ATHENS, Greece (AP) — Greece’s Supreme Court on Wednesday postponed until December an extradition hearing for Russian cybercrime suspect Alexander Vinnik, wanted in the United States on charges of laundering billions of dollars’ worth of bitcoin.

Vinnik is the subject of a judicial tug-of-war between the U.S. and Russia, which is also seeking his extradition on lesser charges. The U.S. is accusing Vinnik of laundering $4 billion worth of bitcoins through BTC-e, one of the world’s largest digital currency exchanges, which he allegedly operated. Russia accuses him of a 667,000-ruble ($11,500) fraud.

Greek courts have approved both extradition requests. The 37-year-old, who denies all charges, is appealing against the decision to extradite him to the U.S. He is not contesting the Russian extradition request.

If Greece’s Supreme Court upholds the lower court’s order, a final decision will rest with Greece’s justice minister.

The Supreme Court set a new hearing date for Dec. 6.

“We asked the court to postpone the hearing today of the U.S. request for the extradition of Vinnik, so that two essential witnesses can come who couldn’t unfortunately come to Athens today,” said Alexandros Lykourezos, one of Vinnik’s lawyers. “These witnesses will be able to testify and help the court understand the essential issues that arise from this case.”

The U.S. Justice Department says Vinnik has been indicted by a grand jury in the Northern District of California on charges including money laundering, conspiracy to commit money laundering, and engaging in unlawful monetary transactions. The charges carry maximum sentences of up to 20 years in prison.

Vinnik was arrested in July on a U.S. request while he was on holiday with his family in the Halkidiki area of northern Greece, which is popular with Russian tourists.