North Korea has acknowledged that it is holding another American, but has so far barred Western officials any access to the detainee, a U.S. official said Friday.

The family of Merrill Newman, a pensioner and Korean War veteran, revealed this week that the 85-year-old was detained on October 26 while on an organized tour of North Korea.

Due to privacy concerns, the State Department refuses to confirm the identity of the person being held.

But spokeswoman Jen Psaki said: "I can confirm that our Swedish protecting power has been informed by North Korea of the detention of a U.S. citizen."

"We are working in close coordination with representatives of the Embassy of Sweden to resolve this issue," she added.

Since Washington and Pyongyang have no diplomatic ties, the Swedish embassy represents U.S. interests in the country, acting as a kind of go-between.

The Swedes had been asking to visit the detained American every day, Psaki said, but "haven't been granted that access."

U.S. Secretary of State John Kerry called Thursday for North Korea to release Newman. Without mentioning him by name, the top diplomat told broadcaster MSNBC that his detention was one of many "disturbing choices by the North Koreans."

The reclusive North is also holding U.S. national Kenneth Bae, a 45-year-old tour operator arrested a year ago as he entered the northeastern port city of Rason.

He was sentenced to 15 years' hard labor on charges of seeking to topple the government.

The court described Bae, also known by his Korean name Pae Jun-Ho, as a militant Christian evangelist who smuggled inflammatory material into the country and sought to establish a subversive base in Rason.

North Korea has in the past freed detained Americans after visits from high-level emissaries. (AFP)