US citizen Matthew Miller sits during his trial at the DPRK Supreme Court in Pyongyang on Sunday.

The Democratic People's Republic of Korea sentenced a 24-year-old US citizen to six years hard labor for committing "hostile acts under the disguise of a tourist", a statement carried by state media said on Sunday.

Matthew Miller joins Kenneth Bae to become the second US citizen serving a hard-labor sentence in the DPRK. A third, Jeffrey Fowle, is awaiting trial.

"He committed acts hostile to the DPRK while entering the territory of the DPRK under the guise of a tourist last April," the short statement said, without elaborating. The Korean version of the statement described Miller's punishment as a "labor re-education" sentence.

Miller, from Bakersfield, California, entered the DPRK in April this year whereupon he tore up his tourist visa and demanded Pyongyang grant him asylum, according to a release from state media at the time. He was traveling on a private trip without foreign guides, according to Uri Tours, the company that organized his trip.

Ripped visa

Pyongyang has not elaborated on Miller's charges, but photos of the trial released by state media showed some of Miller's personal possessions, including his passport, phone, notebook and DPRK visa - which appeared to be ripped. Miller was also shown sitting in a witness box, flanked by DPRK soldiers.

Pyongyang has yet to announce a trial date for Fowle, 56, from Miamisburg, Ohio, who was arrested in May after allegedly leaving a Bible under a bin in the bathroom of a sailor's club in the eastern port city of Chongjin.

A source familiar with the case told Reuters why Fowle left the Bible behind is unclear, but added that Fowle did not seem to be overtly religious.

Bae has been held by the country since December 2012 and is serving a 15-year hard-labor sentence for crimes Pyongyang said amounted to a plot to overthrow the state.

Earlier this month, international media were granted rare access to the three detained US citizens, who in separate interviews all called on the United States to secure their early release.

'Citizens as pawns'

Pyongyang, which is under heavy United Nations sanctions related to its nuclear and missile programs, is believed to be using the detained US citizens to extract a high-profile visit from Washington, with whom it has no formal diplomatic relations.

The US State Department has repeatedly called on the DPRK to release Miller, Bae and Fowle. Assistant Secretary of State Daniel Russel, the senior US diplomat for East Asia, said on Friday that the three US citizens were being used as "pawns" and their detention was "objectionable".

Pyongyang has in the past released detained US citizens to separate delegations led by former US presidents Bill Clinton and Jimmy Carter.

Tourism to the DPRK has increased markedly in the past few years, despite the recent string of arrests, with some operators estimating a tenfold increase in Western visitors over the last 10 years.

"Although we ask a series of tailored questions on our application form designed to get to know a traveler and his/her interests, it's not always possible for us to foresee how a tourist may behave during a DPRK tour," said Andrea Lee, CEO of Uri Tours, the US-based company that organized Miller's trip to the country.

Reuters-AP-Xinhua