SEOUL, South Korea (AP) — A China-based travel agency said Saturday an American university student recently detained by North Korea is being held over an unspecified incident at his hotel before he was scheduled to board a flight for Beijing.

North Korea announced his detention on Friday in a state media report accusing Otto Warmbier of committing a "hostile act" orchestrated by the U.S.

Gareth Johnson, the CEO of Young Pioneer Tours, confirmed via email Saturday that Warmbier had been staying at Pyongyang's Yanggakdo International Hotel and was not with other tourists when the incident occurred. The company statement said Warmbier was detained at the Pyongyang Airport on Jan. 2, but didn't explain what exactly happened at the hotel.

The company said in its statement that an airport official told one of Young Pioneer's guides after Warmbier was detained that he had been taken to a hospital. The guide attempted to go back to see him, but was unable to as airport staff ushered her through immigration, the company said. The company later learned "there had been an incident," according to the statement.

Warmbier is from Wyoming, Ohio, and was studying finance at the University of Virginia.

The U.S. and South Korea have been pushing for tough sanctions against the North over its latest nuclear test on Jan. 6. North Korea has detained a few Americans, South Koreans and other foreigners in recent years, accusing them of anti-North activities in what analysts say are attempts to wrest outside concessions.