South Korean President Roh Moo-Hyun hardened his tone on North Korea yesterday, the opening day of his US tour and three days ahead of a crucial summit with US President George W Bush.

The South Korean leader, on a week long maiden visit to the US, urged Pyongyang to irreversibly scrap its nuclear weapons drive.

"For world peace and security on the Korean peninsula, North Korea must abandon its nuclear development and destroy whatever nuclear materials it possesses," Roh said in a meeting with ethnic Korean residents in New York, the first stop of his US trip.

Roh's remarks were seen as toughening his stand against North Korea's nuclear weapons drive. He has mostly steered clear of direct criticism of Pyongyang, preferring to focus on his search for a peaceful and diplomatic settlement to the crisis.

He vowed to reassure Bush of his policy that he will never condone North Korean nuclear weapons, while reiterating his long-held wish "that the nuclear issue will be resolved peacefully".

The 56-year-old South Korean leader was on a crucial mission to repair damage done to bilateral ties by the North's nuclear weapons drive, anti-US sentiment in South Korea, and simmering trade friction across the Pacific.

In the five months since his election, Roh, who has never visited the US and has little foreign policy experience, has faced the North Korean nuclear crisis and the consequences of a nationwide eruption of anti-Americanism in South Korea.

The former human rights lawyer, who vowed never to "kowtow" to Washington, benefited considerably from anti-US sentiment to beat a pro-US conservative in the December vote.

Roh, who advocates engagement between Seoul and Pyongyang, had undiplomatically criticized the US hard line stance and opposed all talk of sanctions or military action to counter the North's nuclear weapons drive.

But his attitude to Washington has changed radically.

Following his election victory, Roh swiftly understood the importance of the US alliance to South Korea's economy. Business leaders warned him that anti-Americanism and the eroding US alliance, rather than the North's security threat, was responsible for a weakening stock market and currency and the collapse of foreign investment.

Shoring up the US alliance will be the key task of his week-long tour to the country, whose highlight will be the summit with Bush on Wednesday in Washington.

"I hope that these talks will confirm our common approach to resolve the North Korea nuclear issue and maintain the important South Korea-US alliance," Roh said on the flight from Seoul to New York.

Roh won the December election pledging to seek a "more balanced" relationship with Washington - another way of saying that South Korea was tired of being pushed around by its big brother.

But he rapidly switched focus amid the escalating nuclear crisis, and has called for a more solid alliance.

On the nuclear issue, Bush and Roh are expected to release a post-summit statement calling for an outright rejection of a nuclearised Korean peninsula.

North Korea offered to ditch its nuclear and missile programs in return for significant economic and diplomatic benefits at April talks in Beijing with US and Chinese negotiators. Washington has declined to respond to what the North described as a "bold" proposal.

Since the crisis erupted in October, the US has insisted that North Korea must verifiably and irreversibly end both its nuclear programs based on plutonium and enriched uranium.

The summit is also to address US plans to realign the 37 000 American troops in South Korea.

Washington reportedly wants to pull back more than 15 000 US troops with the 2nd Infantry Division from the frontlines with North Korea. – Sapa.