Activists rally for 'martyr' held in North Korea

The activists who gathered in the South Korean capital called on the North's leader Kim Jong-Il to "repent" for his country's rights abuses and described the detainee, Robert Park, as a martyr.

The North said Tuesday it had detained an American for illegal entry from China, its first apparent reference to Park. It said the man, whom it did not name, was under investigation.

Park, 28, was reported by colleagues to have crossed the frozen Tumen River from China on Christmas Day in a protest against repression in the hardline communist North.

A US citizen of Korean ancestry, he claimed he had seen a vision from God of North Korea's liberation and redemption, his colleagues said, adding that Park crossed the border shouting, "I came here to proclaim God's love".

Park carried a letter calling on Kim Jong-Il to release political prisoners, shut concentration camps and take steps to improve rights and conditions.

The US State Department in its rights report says the North is believed to hold 150,000-200,000 people in political prison camps.