PALO ALTO (REUTERS) - North Korea has detained an 85-year-old Korean War veteran from California visiting the country as a tourist, pulling him off a plane as he was about to leave last month, his son said on Wednesday.

Mr Merrill Newman, a retiree from Palo Alto, California, was taken away a day after he and his tour guide spoke with North Korean authorities during a meeting in which his military service in Korea was discussed, his son, Mr Jeff Newman, said in a CNN interview.

His son, who lives in the Los Angeles suburb of Pasadena, said his account of his father's disappearance and the meeting that preceded it was based on details relayed to him through another American travelling with his father at the time.

"I understand that my dad was a bit bothered but really didn't go into any detail (about the meeting) with his travelling companion," the son said in the telephone interview.

The younger Newman went public about his father's detention hours after Japan's Kyodo News Service, citing an unnamed diplomatic source in a dispatch from Beijing, reported that an elderly American man who had entered North Korea with a valid visa for sightseeing last month may have been detained. The report did not identify him.

Neighbours of the elder Newman in northern California told Reuters on Wednesday they were concerned about his fate after he travelled to North Korea but failed to return.

The San Jose Mercury News reported earlier that Mr Merrill Newman was taken off a plane as he was about the depart the reclusive country on Oct. 26.

The detention could become another diplomatic bargaining chip for North Korea, which has held Mr Kenneth Bae, a Korean-American Christian missionary, since November 2012. He has been sentenced to 15 years of hard labour.

The US State Department echoed US Embassy officials in Beijing and Seoul who said they were aware of the reports but could not confirm them.

Mr Jeff Newman told CNN, however, that his family has been in contact with the State Department and had arranged for heart medication needed by his father to be delivered to the North Koreans through Swedish diplomats.

Of the meeting his father had with North Korean officials the day before his detention, Mr Jeff Newman said: "The Korean War was discussed and my dad's role in the service, and the meeting concluded."

The elder Newman and his companion went to dinner that night, he told CNN, and "the next morning, they got up, checked out of the hotel, went to the airport, got on a plane.

"Apparently five minutes before they were ready to depart, an authority came on the plane ... asked to see my dad's passport, and he was asked to leave the plane."

A recent newsletter from Channing House, the Palo Alto retirement home where Mr Merrill Newman lives, identified his companion as another resident, Mr Bob Hamrdla, and said that the two were to be accompanied by Korean-speaking guides at all times on their 10-day trip.

"There has to be a terrible misunderstanding. I hope that the North Koreans will see this as a humanitarian matter and allow him to return to his family as soon as possible," Mr Hamrdla said in a brief statement released by Channing House on Wednesday that provided no further details.

Mr Newman's son said his father had arranged his trip with a travel agent said to have been approved by the North Korean government for travel by foreigners and that he "had all the proper visas."

The elder Newman served as a US infantry officer in the Korean War, later worked as a manufacturing and finance executive and retired in 1984, according to a biography of him in a February 2012 newsletter from Channing House.

Mr Hamrdla, a former assistant to the president of Stanford University who moved into Channing House in 2011, did not return calls. He has led more than 40 study and travel programs to Central Europe, according to a biography on the Stanford website.

A State Department advisory to American travellers warns that"US citizens crossing into North Korea, even accidentally, have been subject to arbitrary arrest and long-term detention."

North Korea says the detained man has broken the law, according to Kyodo.