He crossed the border near the city of Tumen in north-east China into North Korea's Onsong County on Monday, the daily said. "I came here because I did not want to serve as a cannon fodder in the capitalist military. I want to serve in the North Korean army," the American was quoted as telling North Koreans, according to the daily.
However his identity including his name and occupation remained unknown, the paper said. The United States said Friday it had been formally told by the North that it was holding a second US citizen and that authorities were investigating to find out the person's identity.
North Korea, which has no diplomatic relations with Washington, informed the United States through its mission to the United Nations in New York, State Department spokesman Philip Crowley told reporters. But the United States was still unaware of the person's name or the circumstances in which he or she entered North Korea, he said.
The United States has asked Sweden, which handles US interests in Pyongyang, to look into the case, he said. The North's official Korean Central News Agency earlier said in a succinct dispatch that authorities had detained an American on Monday for crossing the border and that he was now under investigation.
Crowley said that the United States understood that it was a fresh case and that the report was not referring to Robert Park, another American held in North Korea. Park, a Christian activist, crossed the border on Christmas Day in an effort to draw attention to human rights concerns in the one-party state.
North Korea is calling for a peace treaty with the United States to end the Korean War armistice and enter diplomatic relations. But the United States says the North must return to six-party talks first to discuss the removal of its nuclear weapons and programmes.