North Korea has arrested a US tourist for "hostile activities", Pyongyang's state media said Friday, bringing the total number of Americans held by the reclusive regime to three.

The official Korean Central News Agency (KCNA) said the man was being questioned, identifying him only in Korean without providing the English spelling of his name.

"US citizen in custody for committing anti-DPRK (North Korea) hostile activities", KCNA said in the headline of a brief dispatch.

"The US Citizen, who entered the DPRK (North Korea) on April 29 as a tourist, engaged in activities that were in breach of DPRK's laws", the report said.

The man is the third US citizen known to be currently detained by the North.

The two others include 24-year-old US tourist Matthew Todd Miller, who was arrested in April after he apparently ripped up his visa at immigration and demanded asylum in the communist state.

Kenneth Bae, described by a North Korean court as a militant Christian evangelist, is also being held in the North after he was arrested in November 2012 and sentenced to 15 years' hard labour on charges of seeking to topple the government.

US efforts to secure Bae's release have so far been unsuccessful.

Last month the US government issued a fresh warning against all travel by US citizens to North Korea, saying that even joining a tour would fail to protect them from arbitrary arrest.

"In the past 18 months, North Korea has detained US citizens who were part of organized tours," State Department spokeswoman Jen Psaki said on May 22.

"A US citizen should not assume that joining a group tour or using a tour guide would protect them from being detained or arrested by North Korean authorities," she added.

Last year, then 85-year-old US Korean war veteran Merrill Newman was held for more than a month in North Korea after inquiring about North Korean veterans, even though he was on a guided trip to the reclusive state.

On his return home to California in December, Newman, who was forced to make a filmed "confession," said he believed North Korean authorities misunderstood his "curiosity as something more sinister."

He had concluded that, "for the North Korean regime, the Korean War isn't over and that even innocent remarks about the war can cause big problems if you are a foreigner".

The United States has no diplomatic or consular relations with the North.

The Swedish Embassy in Pyongyang provides limited consular services to US citizens travelling in North Korea who are ill, injured, arrested, or who have died while there. (AFP)