The United States has said it does not intend to press for immediate sanctions against North Korea.

The crisis over the Stalinist state's nuclear programme was referred this week to the UN Security Council, which could make such a move.

Pyongyang has warned it could hit US targets across the world

American envoy Richard Williamson insisted that the US - which pressed for the council's involvement - was still keen to solve the crisis diplomatically.

But North Korea said his remarks were untrustworthy, and maintained that the dispute could only be resolved by direct negotiations between Washington and Pyongyang.

North Korea has previously warned that it would regard the imposition of sanctions as a declaration of war.

The relationship between North Korea and its southern neighbour has been soured by the crisis. Talks on economic co-operation ended on Thursday without agreement, as South Korea said the nuclear impasse must be resolved first.

But despite the increasing tensions, for the first time in more than 50 years, a party of South Korean nationals crossed the overland border for a tourist trip into the North on Friday.

Diplomatic solution

US envoy Richard Williamson told reporters at the UN that sanctions against Pyongyang were "not an issue right now".

CRISIS CHRONOLOGY

16 Oct: US announces that N Korea has acknowledged secret nuclear programme 14 Nov: US halts oil shipments to N Korea 22 Dec: N Korea removes monitoring devices at Yongbyon nuclear plant 31 Dec: UN nuclear inspectors forced to leave North Korea 10 Jan: N Korea pulls out of anti-nuclear treaty 28 Jan: President Bush urges the "oppressive" N Korean regime to give up its nuclear ambitions 12 Feb: IAEA refers issue to Security Council

Secretary of State Colin Powell said: "We still think there is the possibility of a diplomatic solution."

North Korea's neighbours - Japan, South Korea, China and Russia - have also urged further talks rather than possible military action.

On Friday Japan sought to clarify remarks that Tokyo would launch a pre-emptive strike against Pyongyang.

"The situation is very tense in North Korea, but Japan is not making any special preparations in response to that," defence chief Shigeru Ishiba told reporters on Friday.

But he stressed that Japan would retaliate with military force if North Korea used arms against it.

The crisis over North Korea erupted in October, when the US said Pyongyang had admitted to a secret nuclear weapons programme.

North Korea subsequently pulled out of the Non-Proliferation Treaty and expelled UN nuclear inspectors.

The UN's nuclear body, the IAEA, referred Pyongyang to the Security Council this week for having been "in chronic non-compliance (with its international nuclear agreements) since 1993".

Tourist first

Around 400 prominent South Korean public figures took part in Friday's overland journey to the North.

Tourists have participated in an historic overland journey

The visit may pave the way for regular trips to the scenic Mount Kumgang, or Diamond Mountain.

The cross-border route is one of several that are being reconnected under agreements signed at the historic inter-Korean summit three years ago.

South Korean President Kim Dae-jung apologised on Friday for his involvement in a scandal surrounding payments to North Korea ahead of the summit.

The border between the two Koreas is heavily fortified by both Korean and US forces, and on Friday US Defense Secretary Donald Rumsfeld raised the possibility of moving some American troops away from the region.

He said no plan had yet been finalised, but South Korea's president-elect Roh Moo-hyun has asked Washington to reassess US troops in the South.

Mr Roh did not want a complete withdrawal of American forces, but sought to "rebalance" the US-Korean military alliance, a US official told Reuters news agency.