The United States welcomed North Korea's release of a US Korean War veteran held for more than a month, and urged Pyongyang to also release another US detainee.

Merrill Newman, an 85-year-old from California, was deported "from a humanitarian viewpoint," the North's official news agency KCNA said, citing his "sincere repentance" as well as his age and health condition as factors for his being freed.

"We are pleased that Mr Merrill Newman has been allowed to depart the DPRK and rejoin his family. We welcome the DPRK's decision to release him," State Department deputy spokeswoman Marie Harf said in a statement.

The elderly Californian with heart problems was plucked off a plane on October 26 as he was leaving Pyongyang following a tourist visit.

His release came as US Vice President Joe Biden visited South Korea, the last stop on a three-country Asia tour that has already taken him to Japan and China.

"The DPRK today released someone they never should have had in the first place, Mr Newman," Biden said, welcoming the news after a wreath-laying ceremony at Seoul's War Memorial of Korea, which honours Korean and American war dead.

A senior administration official from the vice president's office said that Newman is now in Beijing.

The vice president, who said he played no direct role in the release, talked to Newman on the phone and offered to give him "a ride home on air force Two," but said that the war veteran had declined.

In welcoming Pyongyang's "positive decision," both Biden and Harf renewed calls for the reclusive country to free another American, Kenneth Bae.

The 45-year-old tour operator was arrested a year ago and sentenced to 15 years' hard labour on charges of seeking to topple the government.

"It's a positive thing they've done, but they still have Mr Bae, who has no reason being held in the North," Biden said.

"We're going to demand his release as well." Harf called on North Korea "to pardon and grant Mr Bae special amnesty and immediately release him as a humanitarian gesture so that he too can return home to his family," she said.

"The US government will continue to work actively on his case." Harf thanked the Swedish government, whose embassy acted on Washington's behalf since the United States has no formal ties with North Korea, for its "tireless efforts." Last week Pyongyang for the first time officially admitted holding Newman, saying he was detained for "hostile acts" after entering the country "under the guise of a tourist." North Korea had accused him of committing crimes both as a tourist and during his participation in the Korean War.

The North also claimed that Newman masterminded espionage and subversive activities during the war and was involved in the killing of North Korean soldiers and innocent civilians.

State media had released a video of Newman, a retired financial executive who spent time in North Korea during the war, confessing to his crimes.

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