North Korea police
North Korea policeReuters

A student from the United States was reportedly detained by North Korean authorities during a tour of the East Asian country for "committing a hostile act against the state". 

Otto Frederick Warmbier -- a 21-year-old University of Virginia student -- was detained at Pyongyang airport on 2 January.

The student's "hostile act" was "tolerated and manipulated by the US government", Reuters cited state-run KCNA news agency. It reported that he aimed "to destroy the country's (North Korea) unity". A US embassy official in South Korean capital Seoul has confirmed the arrest.

China-based travel agency Young Pioneer Tours (YPT) that organised Otto's travel to North Korea confirmed his detention. "We are in contact with the Swedish Embassy, (who act as the protecting interest for U.S citizens), who are working with the Ministry of Foreign Affairs to address the case," YPT said.

Otto was in North Korea on a five-day New Year trip when he was detained by the country's officials, Gareth Johnson of YPT said. "We are in touch with Otto's family, the US State Department and the Embassy of Sweden in Pyongyang and doing all we can to secure his release," Johnson told Reuters.

Tensions between North Korea and the US have increased over the last few weeks after the former claimed to have tested a hydrogen bomb on 6 January. 

The US on Wednesday said it will impose tougher sanctions on North Korea if China fails to act against its ally's nuclear weapons programme. China is North Korea's most important partner in trade of food, arms, and energy.

"I think what we will be talking to China about is that we will, both in terms of sanctions and in terms of our defense postures, have to take additional steps in order to use the leverage we have in order to defend ourselves and our allies if North Korea doesn't change its behaviour," The New York Times quoted Deputy Secretary of State Antony J Blinken as saying.