Bosworth has been appointed to the role previously held by Christopher Hill, a career diplomat who is expected to move to a new position as US ambassador to Iraq.

The six-party talks hosted by China and involving Japan, Russia, the US and the two Koreas stalled late last year amid disagreement over the procedures for verifying North Korea's disarmament steps.

Under a landmark deal in 2007, North Korea agreed to scrap its weapons-grade nuclear programmes in exchange for badly-needed energy aid.

But negotiations hit a deadlock late last year when North Korea balked at US demands for verifying the shut down.

Bosworth's trip to Asia comes amid escalating tensions on the Korean peninsula, with the North reportedly preparing to launch a rocket carrying what it says is an experimental communications satellite, but which many believe is a test of a long-range missile.

Rare dialogue

North Korean and US-led UN command officers shown here at the last meeting in 2002 [AFP]

On Monday North Korea demanded that the US call off joint military exercise with South Korea due to begin next week, saying the exercises would only stir up tensions and the likelihood of war.

The call came during rare talks between generals from the North and the US-led UN command at the border village of Panmunjom, South Korea's Yonhap news agency said.

The UN command said in a statement the North requested the meeting, which lasted half an hour, to "discuss issues of mutual trust and tension reduction".

Yonhap quoting an unnamed South Korean official said the North warned that the upcoming military drill would "further stir up" tensions in the region.

The meeting was the first direct contact between the two sides in almost seven years.

Pyongyang has regularly denounced the exercise as preparation for an invasion and a nuclear war.

The UN command has insisted that the exercise involving 26,000 US troops and an unspecified number of South Korean soldiers and US aircraft carriers is purely defensive.

Missile interceptor

Pyongyang says the US-South Korea military exercises are a pretext for invasion [EPA]

During his trip to Asia, Bosworth is expected to step up efforts to deter North Korea from going ahead with its rocket launch.

The US, South Korea and Japan have all warned Pyongyang that any such move would be in violation of a UN Security Council resolution, which could spell further sanctions for the isolated nation.

On Tuesday Japanese officials said they were considering deploying ballistic missile interceptor warships to the Sea of Japan if North Korea's preparations become more active, the Kyodo news agency reported.

A defence official was quoted as saying that two naval destroyers with advanced Aegis radar systems and missile interceptors would be sent to the sea region between Japan and the Korean peninsula.

Kyodo also quoted the official as saying that Japan will be cooperating with the US, which has also stationed anti-ballistic missile ships in the country.

The US has 28,500 troops stationed in South Korea to support its 680,000-strong military against North Korea's 1.1 million troops.

Taro Aso, the Japanese prime minister, has indicated that Japan should be able to use its missile defence capabilities even if North Korea insists that it is launching a satellite.