The prospect of the ongoing six-party on the Korean Peninsular nuke issue remained hazy although the talks are said to end today.

The chief negotiators of the Democratic People's Republic of Korea (DPRK) and the United States held two rounds of one-on-one meetings on Thursday, the Chinese press center said, without releasing details of their talks.

The top U.S. envoy Christopher Hill, after a third straight day of one-on-one talks with his DPRK counterpart, said he had a "long and difficult" day.

"Today was a not a day when we registered much progress..the talks are expected to end on Friday," he said.

Clearly dissatisfied with the DPRK's emphasis on the financial issue,Hill stressed that "it's time to talk the denuclearization and discuss the implementation of the joint statement" in September 2005.

Under the joint statement, the DPRK agreed to abandon its nuclear program in exchange for economic aid and security guarantees.

Formally known as the second phase of the fifth round since 2003, the talks resumed on Monday after a 13-month suspension and involved China, the DPRK, the United States, the Republic of Korea,Japan and Russia.

As the talks entered the fourth day on Thursday, a flurry of one-on-one negotiations were held in the Diaoyutai State Guesthouse.

Host China also stepped up its diplomatic efforts on Thursday by holding direct meetings with the other five parties, aiming at narrowing down their differences.

Yet some envoys said there is little chance of breakthrough this week.

"The situation of the talks remains severe, and there is no prospect of breakthrough up to now," Japan's top negotiator Kenichiro Sasae told reporters in the hotel Thursday evening.

The DPRK "holds a very strong position on the financial issue, which is currently the biggest difficulty in the talks," Sasae said.

Financial sanction imposed on the DPRK was one of the key stumbling blocks that had stalled the six-party talks for the past13 months.

On Thursday morning, U.S. treasury officials headed back to Washington after they held two rounds of talks with their DPRK counterparts on Tuesday and Wednesday.

Daniel Glaser, who was leading the U.S. treasury delegation, said the meetings were business-like and useful, but hinted that no progress came out of the financial talks.

Glaser said he might meet with the DPRK counterpart next month in New York.

"There is no point getting too pessimistic or optimistic each day," Hill said.

On Friday, Hill will meet again with the chief DPRK negotiator Kim Kye-gwan.

"We have to see whether tomorrow will be a better day," Hill said, adding he will leave Beijing Saturday morning.