South Korea responded by saying that it would halt aid to the impoverished communist North after the negotiations ended a day earlier on Thursday.

The talks were called after North Korea test-fired seven missiles off its eastern coast last week.

A high-ranking South Korean official said: "We're going to (withhold aid) until we see an exit out of this situation.

"As to what the exit is, I think the most important thing is North Korea's return to six-party talks."

Six-nation talks

The North has boycotted the six-nation discussions on the future of its nuclear programme since last year in protest at financial restrictions imposed by Washington.

North Korea said this week's talks had failed because Seoul had said that the North should join the six-nation meetings which include China, Japan, Russia, the US and South Korea.

"The South side created an artificial obstacle to the talks, without discerning where the military threat to the Korean Peninsula comes from," the North Korean delegation said. "North-South high-level talks are never military talks or six-party talks."

Sanctions

North Korea is under Western pressure to halt its nuclear programme. Japan called for UN sanctions against Korea after the recent missile tests, although China is likely to block any such measures.

South Korea's decision to halt aid may be more telling. The South is a major supplier of aid to the North, sending rice and fertiliser to help the country's depleted agricultural sector.

South Korean and US Marines at a joint exercise in 2006

The North had requested 450,000 tons of fertiliser and 500,000 tons of rice this year. The South has already shipped 350,000 tons of the fertiliser.

"Of course, rice and fertiliser is a humanitarian issue. ... But I think that under this situation, peace is also a humanitarian issue," the South Korean official said.

South Korea's warning

South Korea warned the North against additional missile launches, saying this would increase regional tensions and damage inter-Korean relations.

But the North has also argued that its policy of strengthening its military gives protection to South Korea too - a claim immediately rejected by the South.

The two Koreas, separated by the world's most heavily fortified border, remain technically at war since the Korean War ended in a 1953 cease-fire, not a peace treaty.