"I think the situation still remains tough. Tomorrow it will become clearer which way it is going, whether the discussions are heading towards a settlement or not," Kenichiro Sasae told reporters.

The latest round of talks -- which began in 2003 and involve host China, the two Koreas, the United States, Japan and Russia -- began on Thursday on a positive note, with China circulating a draft accord on a potential deal.

The plan calls for Pyongyang to begin taking steps towards ending its nuclear programme in return for economic incentives, but has snagged on what Sasae said earlier Sunday were North Korea's "excessive" demands for energy aid.

Sasae said following the end of Sunday's talks that the day's events had been held in a more tense atmosphere than the previous day, and that energy remained one of the biggest sticking points.

"It is indeed one of the biggest issues," he said, when asked about the debate over energy.

North Korea, apparently emboldened by its October detonation of a nuclear device, has demanded two million tonnes of fuel oil and other inducements, Japanese press have reported.

That would be four times as much fuel oil as offered under a now-defunct 1994 disarmament deal.

All rights reserved. © 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.