Otto Warmbier, the American university student being held by North Korea, was detained before boarding his flight to China over an unspecified incident that had taken place at his hotel, his travel company says.
North Korea's official KCNA news agency said on Friday that Warmbier "was caught committing a hostile act against the state", which it said was "tolerated and manipulated by the US government".
Charlotte Guttridge, a tour leader at Young Pioneer Tours and the only outside witness to Warmbier's detention, said on Saturday the 21-year-old University of Virginia student was not with other tourists when the events that appear to have prompted his arrest occurred.
"What happened, happened at the hotel and my belief is that Otto kept it to himself out of hope it might go unnoticed," Guttridge told Reuters.
Guttridge and colleagues at Young Pioneer Tours declined to share further details of exactly what had taken place, citing the safety of their client.
Warmbier had been staying at the Yanggakdo International Hotel when the incident that led to his arrest occurred. The Yanggakdo is a towering structure on an island in the middle of the Taedong river, which cuts through central Pyongyang.
China-based Young Pioneer Tours is a North Korea travel specialist that describes itself on its website as "an adventure tour operator that provides 'budget tours to destinations your mother would rather you stayed away from'".
During his five-day New Year's tour of North Korea, staff at Young Pioneer Tours said Warmbier had acted normally, and was keen to see daily life in one of the world's most isolated countries, which is visited by around 6000 Western tourists a year. Ten other US citizens were on the tour.
"Throughout the trip, Otto behaved as a typical tourist - taking pictures, enjoying himself. We had no indication that anything untoward had happened until the airport," Guttridge said.
