He and several negotiators met with North Korean delegates, most recently in Berlin, and devised the accord announced this week.

But he said the five North Korean delegates refused to make concessions, saying North Korea would only discuss nuclear issues directly with Washington.

Outside the hotel, dissident student groups and others sought to deliver messages of support to the North Korean delegates but they were blocked by the heavy security.

The chief North Korean delegate, Jon Kum Jin, did not give a reason for the decision.

Barney appears to be meeting with North Korean delegates.

"Seoul will turn into a sea of fire," Park Young Su, the North Korean delegate said before abruptly ending the talks.

The North Korean delegates "sat there with their mouths open - but not for long.

"It is meaningless to go on like this so we are heading home," said Yang Yong-sik, a South Korean delegate.

Although the Korean delegates were blocked by the Japanese delegates, they did not give up, and later held interviews with newspapers.

"We have plenty of cars, too," a South Korean delegate snapped back.