SEOUL: US envoy Stephen Bosworth ended a three-day visit to North Korea Thursday, reportedly saying he had "very useful" meetings aimed at bringing the communist state back to nuclear disarmament talks.

His trip was the first official contact between Washington and Pyongyang since US President Barack Obama took office in January, pledging direct diplomacy with adversaries.

"It's a very useful meeting," China's Xinhua news agency quoted Bosworth as saying at Pyongyang's Sunan Airport before returning to South Korea.

Bosworth is due to brief South Korean Foreign Minister Yu Myung-Hwan and chief nuclear negotiator Wi Sung-Lac before holding a press conference around 6:00 pm (0900 GMT), Seoul officials said.

The North quit the six-nation nuclear disarmament negotiations in April before staging its second atomic weapons test the following month.

Washington says Bosworth's mission was solely to assess whether the North is willing to return to the negotiations, and whether it will reaffirm its commitment to a denuclearisation accord reached in 2005. Related article: Kim Jong-il out of town

Analysts, however, say Pyongyang appears to be pushing for a peace treaty with the United States to formally end the 1950-53 Korean War.

Washington says this can only be discussed multilaterally after the six-party forum -- which groups the two Koreas, the United States, China, Russia and Japan -- is resumed.

Bosworth's trip capped a turbulent year. Stung by international censure of its long-range rocket launch, the North in April declared the six-party talks "dead". It later announced resumed production of weapons-grade plutonium.

In May it staged its second nuclear test and followed up with a series of missile launches in July, attracting tougher UN sanctions.

Later in the year the North began striking a softer note in what some analysts saw as a bid to soften the sanctions. In August it handed over two jailed US reporters to visiting former president Bill Clinton.

In October the North told key ally China it was ready to return to the six-nation talks, but only if direct dialogue with the United States proves satisfactory.

Obama has offered the isolated and impoverished nation security and prosperity if it honours its 2005 commitment to give up nuclear weapons.

But a senior US official warned this week the North could expect continued "very strong enforcement" of sanctions if it continues shunning the six-party forum.