ATHENS – Further straining relations between them, Russia is upset that Greece extradited to the United States a Russian wanted for allegedly being involved in a massive bitcoin theft scheme.

Russian Foreign Ministry spokesperson Maria Zakharova said extradition of Alexander Vinnik, also known as “Mr. Bitcoin,” was in violation of the Vienna Convention on Consular Relations of 1963 said Kathimerini.

He was arrested in Greece in 2017 while on a vacation with his family and had been the subject of attempts by the US to get its hands on them, becoming a tense international issue. He was being held in France, which returned him to Greece for the extradition, said The Moscow Times.

“We are outraged by the unfriendly actions of the Greek authorities, who, under pressure form the United States, which launched a real hunt for Russian citizens in third countries under far-fetched pretexts, extradited our compatriot Alexander Vinnik to be published by American punitive justice,” Zakharova said.

She added that “Russian diplomats will do everything possible to protect his legitimate rights and interests,” ties with Greece already worsened after Greece backed European Union sanctions over Russia’s invasion of Ukraine and booting Russian diplomats.

Vinnik is accused of operating a cryptocurrency exchange known as BTC-e that allegedly did business with ransomware gangs, drug dealers and identity thieves, according to the Justice Department, said CNN.

He faces charges in alifornia of money laundering and operating an unlicensed money service business in the US, among other charges, the extradition seen a big win for the US to gain custody of him.

Vinnik’s extradition shows how US prosecutors have continued to pursue high-profile Russian cybercrime suspects after relations with Russia have become even more tense than before.

BTC-e, which shut down in 2017, received more than $4 billion worth of bitcoin while it was operating, according to the Justice Department.

The Treasury Department in 2017 assessed a $110 million civil money penalty against the cryptocurrency exchange “for willfully violating U.S. anti-money laundering laws” and a $12 million fee against Vinnik, added CNN.