A Korean American detained for six months in North Korea has been sentenced to 15 years of hard labour for "hostile acts" against the state, the North's media said Thursday — a move that could trigger a visit by a high-profile American if history is any guide.

Kenneth Bae, a Washington state man described by friends as a devout Christian and a tour operator, is at least the sixth American detained in North Korea since 2009. The others eventually were deported or released without serving out their terms, some after trips to Pyongyang by prominent Americans, including former U.S. presidents Bill Clinton and Jimmy Carter.

With already abysmal U.S.-North Korean ties worsening since a long-range rocket-launch more than a year ago, Pyongyang is fishing for another such meeting, said Ahn Chan-il, head of the World Institute for North Korea Studies think-tank in South Korea.

"North Korea is using Bae as bait to make such a visit happen. An American bigwig visiting Pyongyang would also burnish Kim Jong-un's leadership profile," Ahn said. Kim took power after his father, Kim Jong-il, died in December 2011.

The authoritarian country has faced increasing criticism over its nuclear weapons ambitions. Disarmament talks including the Koreas, the United States, Japan, China and Russia fell apart in 2009. Several rounds of UN sanctions have not encouraged the North to give up its small cache of nuclear devices, which Pyongyang says it must not only keep but expand to protect itself from a hostile Washington.

Pyongyang's tone has softened somewhat recently, following weeks of violent rhetoric, including threats of nuclear war and missile strikes. There have been tentative signs of interest in diplomacy, and a major source of North Korean outrage — annual U.S.-South Korean military drills — ended Tuesday.

Bae was arrested in early November in Rason, a special economic zone in North Korea's far northeastern region bordering China and Russia, North Korea said.

The trial mirrors a similar situation in 2009, when the U.S. and North Korea were locked in a standoff over Pyongyang's decision to launch a long-range rocket and conduct an underground nuclear test. At the time, North Korea had detained two American journalists, whose eventual release after being sentenced to 12 years of hard labour paved the way for diplomacy following months of tensions.

"The Supreme Court sentenced him to 15 years of compulsory labour for this crime," the Korean Central News Agency said.

The exact nature of his alleged crimes has not been revealed.

In North Korean dispatches, Bae, a Korean-American from Washington state, is called Pae Jun Ho, the North Korean spelling of his Korean name.

U.S. State Department spokeswoman Jen Psaki said last week that officials from the Swedish Embassy in Pyongyang had visited Bae on Friday. She said she had no other information to share.

Because Washington and Pyongyang do not have diplomatic relations, the Swedish Embassy in North Korea represents the United States in legal proceedings.

Fed North Korean orphans, friends say

Friends and colleagues said Bae was based in the Chinese border city of Dalian and travelled frequently to North Korea to feed the country's orphans.

KCNA on Thursday described Bae as a "tourist" who was arrested while committing "hostile acts" against North Korea.

At least three other Americans detained in recent years also have been devout Christians. While North Korea's constitution guarantees freedom of religion, in practice only sanctioned services are tolerated by the regime.

In 2009, American journalists Laura Ling and Euna Lee were sentenced to "hard labour" for trespassing and unspecified hostile acts after being arrested near the border with China and held for four months.

They were freed later that year to former president Bill Clinton, who flew to Pyongyang to negotiate their release in a visit that then leader Kim Jong-il treated as a diplomatic coup.

Including Ling and Lee, Bae is at least the sixth American detained in North Korea since 2009. The others eventually were deported or released.