US ambassador to Seoul Stephen Bosworth said in an interview with the Yonhap news agency the two sides were set to agree to South Korea extending its missile range under the Missile Control Technology Regime (MCTR).

He said South Korea and the United States were in the "final stages" of negotiations over the deal and were due to hold a last round of talks soon.

South Korea's existing missile range is limited to 180 kilometres (112.5 miles) under a bilateral agreement with the United States.

The MCTR, an international agreement with 32 member countries, allows for development of missiles up to a maximum range of 300 km (187.5 miles) capable of carrying a 500 kilogram payload.

"We are in the final stages of successful negotiations which would have important benefits in enabling South Korea to join the MTCR," Bosworth said.

Asked if joining the MTCR would enable South Korea to extend the range of its missiles, Bosworth said: "Longer range than it currently has under the bilateral agreement (with the United States). It would be able to go out further."

A senior official in South Korea's Foreign Ministry confirmed the negotiations.

Shin Min-Ho, deputy director of the ministry's North American division, said attempts to develop South Korean rockets had been hampered by non-membership of the MTCR.

"We are trying to develop our rocket system. But if we are not members of MTCR we are not able to buy parts," Shin said, playing down suggestions any extension could threaten its neighbours.

"We don't think it will. It's a very short range...we don't think it will be a threat," he said.

"North Korea might consider that this extension of our capacity is contrary to present co-operation but by joining the MTCR we are showing total transparency of our programme. The MTCR is very clear," he said.

Park said there remained "three or four" points which needed to be resolved before South Korea's membership could be confirmed.

Robert Einhorn, US assistant secretary of state for arms non-proliferation would visit Seoul on July 14 for informal talks, Shin said, adding South Korea hoped to confirm MTCR membership by the end of this year.

The negotiations follow last month's Pyongyang summit, which was regarded as a sign that the Stalinist nation wants to reconcile with its former Korean War foes.

The United States eased economic sanctions against the North following the summit. Shortly afterwards, North Korea announced that it would stick to a moratorium on missile tests, agreed in 1994.

The apparent thaw in relations has raised questions over the United States' continued heavy military presence in South Korea, where some 37,000 personnel are stationed.

But Bosworth said forward deployment of troops would continue to be a key plank of US security policy in the region.

"We are here because people and the government of South Korea feel threatened.

"As long as that sense of threat continues, we will remain here as we are now," he said, hailing last month's summit as "a very important strategic change" on the part of North Korea.

North and South Korea have remained technically at war since the end of their bitter 1950-53 conflict. No armistice has ever been signed between the two sides.