LONDON -- Gordon Black, the U.S. soldier detained in Russia, has "admitted guilt" on a charge of theft, according to TASS, a state-owned news service.
Black was said to be "cooperating" with Russia's investigation into the alleged theft, TASS reported on Thursday.
"The accused admitted guilt and is cooperating with the investigation. This is happening in English through an interpreter," TASS reported, quoting a representative of local law enforcement agencies.
Black was detained in Vladivostok, Russia, earlier this month on charges of criminal misconduct, according to the U.S. Army. His detention is expected to last until at least July 2, according to the court. His lawyer had appealed his detention last week.
Two U.S. officials told ABC News this month that Black, a staff sergeant, had been stationed in South Korea before going on temporary leave. He was not granted permission to travel to Russia, the officials said.
Black had traveled to Russia to visit his girlfriend, the 35-year-old's mother, Melody Jones, told ABC News' "Good Morning America" last week.
TASS reported on Thursday that Black and the woman had a disagreement while he was visiting her in Vladivostok, a far-eastern city near the borders with China and North Korea.
"After Black left, his friend discovered the missing money and turned to law enforcement for help," TASS reported. "The police found the suspect in the theft in one of the city hotels."
Black had purchased a return flight, the outlet said.
ABC News' Ellie Kaufma, Joe Simonetti, Leah Sarnoff, Mark Guarino and Anne Flaherty contributed to this report.