Amnesty International has hit out at North Korea's treatment of people of faith following reports that an American tourist was detained in the closed communist country last month.

Jeffery Edward Fowle, 56, from Miamisburg, was seized by authorities in May because he "perpetrated activities that violated the laws of our republic, which did not fit his stated purpose of visiting our republic as a tourist", the state-run news agency KCNA said.

Japanese news outlets reported that his detention may have been prompted by leaving a Bible in his hotel room.

A statement by Mr Fowle's lawyer, Timothy N Tepe, did not verify the reports about the Bible, but commented instead that his wife and children were missing him "very much and are anxious for his return home".

Amnesty International's East Asia research director, Roseann Rife, said there was "close to zero chance" of a fair trial for Mr Fowle.

The human rights organisation is calling upon North Korea to release all those detained solely for their religious beliefs.

"Leaving behind a Bible in a hotel room, whether by accident or by design, should never amount to a criminal offence," she said.

She added: "North Korea's court system makes a mockery of justice."

Other Americans being held by North Korea are Christian missionary Kenneth Bae, who was sentenced to 15 years of hard labour in April 2013, and Matthew Todd Miller, 24, who KCNA said was detained after demanding asylum following his arrival in the country.