Envoys from North and South Korea, China and the United States set to work Monday on a new round of treaty talks meant to ease decades of tensions on the divided Korean Peninsula.

Leaders of delegations from the four nations met informally Monday, but the opening of the plenary session in Geneva was temporarily delayed, South Korean officials said. The officials, who spoke on condition of anonymity, gave no reason for the delay.The main item on the agenda is a permanent peace treaty to replace the armistice that ended fighting in the 1950-53 Korean War.

Most observers expect that to take years. In the meantime, it is hoped that the talks will build confidence between the South and the Communist North and reduce the risk of a military flare-up.

The negotiators were tight-lipped but appeared upbeat as they entered the conference center where the talks are to be held.

"I'm glad to be here," Chinese Assistant Foreign Minister Chen Jian, head of his country's delegation, told reporters gathered outside.

China, one of the isolated North's last remaining allies, will lead the Geneva meeting, which may last all week. The United States, the South's main defender, will be the other mediator at the talks.

The meeting is a follow-up to an initial two-day session last December. Regular meetings, two or three months apart, are expected to follow.

Apart from helping the longstanding foes get acquainted, the first round of talks achieved little. This was largely because of the North's insistence that the agenda should include the withdrawal of the 37,000 American troops from South Korea.

Although the Pyongyang delegation is expected to repeat those demands this time around - and the delegations from Seoul and Washington are expected to reject them - it is also hoped that there will be more substantive discussions.

Prospects for success are mixed.

South Korea's new president, former dissident Kim Dae-jung, has made improving relations with the North a top priority.

Meanwhile, North Korea has indicated it is willing to start an inter-Korean dialogue in parallel with the Geneva process. For years Pyongyang refused to talk directly with previous governments in Seoul.