Russia said Tuesday it will keep in custody until early July an American soldier detained in the Far East over the weekend on theft charges.

The US Army said the soldier, identified by a Russian court in Vladivostok as Gordon Black, was being held on criminal charges, but did not provide details, citing the sensitivity of the case.

Black's detention increases the number of Americans held in Russia at a time of deep tension with Washington over Moscow's full-scale invasion of Ukraine.

A Russian court spokeswoman said Black, who was detained on May 2, will be detained until July 2 for theft, according to comments from the state news agency RIA Novosti.

The Russian tabloid Izvestia and the Baza Telegram news channel, which is suspected of having ties to law enforcement, said Black beat his Russian girlfriend during a visit to Vladivostok and stole money and alcohol from her.

NBC News reported that the American soldier came to Russia on his own and was not there on official business.

White House National Security Council spokesman John Kirby said late Monday that Washington is aware of Black's arrest in Russia.

Russian authorities have arrested several US citizens in recent years, and critics have accused Moscow of using the detainees as bargaining chips in exchange for Russians jailed in the West.