Seoul  - The top diplomats of the United States and South Korea urged North Korea Friday to end its threats toward Seoul and unconditionally return to the negotiating table.

US Secretary of State Hillary Rodham Clinton and South Korean Foreign Minister Yu Myung Hwan said after meeting in Seoul that their countries would in no way accept a nuclear-armed North Korea, according to a statement released by South Korea's Foreign Ministry.

Clinton called North Korea's "war of words" "provocative and unhelpful" and urged it to engage with South Korea while also announcing the appointment by US President Barack Obama of his top negotiator with North Korea, Stephen Bosworth, a former US ambassador to South Korea.

Clinton and Yu called for the resumption of six-nation talks aimed at dismantling North Korea's nuclear weapons programme. Both countries are involved in the talks along with North Korea, China, Japan and Russia.

"We are calling on the government of North Korea to refrain from being provocative and unhelpful in a war of words that it has been engaged in because that is not very fruitful," Clinton said.

The two diplomats also agreed to strengthen their military alliance. The United States has 28,500 soldiers stationed in South Korea as a deterrent to North Korea.

Clinton's trip to Seoul came amid escalating threats from North Korea. On Thursday, its military warned that it was prepared for "an all-out confrontation" with its neighbour on the Korean Peninsula.

The North Korean People's Army also threatened an open military conflict with the South in January, saying President Lee Myung Bak and his "puppet military war hawks" would force it "to take a strong military retaliatory step to wipe them out."

South Korea fears tensions with its Stalinist neighbour could escalate into a limited military altercation, possibly over the two countries' contested border in the Yellow Sea.

Relations between the Korean Peninsula neighbours have soured since Lee took office a year ago, scrapped the so-called Sunshine Policy of his liberal predecessors and adopted a tougher course toward Pyongyang, demanding progress in dismantling the North's nuclear weapons programme in exchange for aid.

Repeated requests by Seoul for dialogue with Pyongyang have been rejected. Instead, Pyongyang has threatened Seoul with annihilation several times over the past weeks and in late January scrapped bilateral reconciliation agreements and nullified an agreement over its sea border with the South. It accused Lee's government of pursuing a confrontational policy.

Clinton arrived Thursday in South Korea during an Asian tour, her first overseas trip after becoming secretary of state last month. The former senator and first lady first visited Japan and Indonesia, and her final stop is China, where she was due later Friday. (dpa)