By Kakumi Kobayashi and Naoko Aoki

BEIJING, June 26 Kyodo - The six-way talks on North Korea's nuclear programs hammered out Saturday its first-ever tangible commitment in seeking a freeze of Pyongyang's nuclear programs and compensation as ''first steps'' toward the goal of denuclearizing the Korean Peninsula.

A breakthrough, however, remained elusive as differences between Washington and Pyongyang lingered over the North's alleged uranium enrichment program -- the thorniest issue that led to the nuclear crisis 20 months ago.

''There is a very serious difference with respect to the uranium enrichment program,'' Chinese Vice Foreign Minister Wang Yi told a news conference wrapping up the third round of the meeting between host China, Japan, North and South Korea, Russia and the United States.

''We hope this question…will be resolved in future talks,'' said Wang, who was chairman of the four-day talks.

He noted ''a serious lack of mutual trust'' among the six nations.

Delegation officials said the uranium issue remained the major stumbling block, and the U.S. and North Korean proposals were too incompatible for concessions to be reached.

A chairman's statement issued after the talks also underlined a failure to agree on exactly how and when North Korea will freeze its nuclear programs, and whether it will commit to dismantling them.

''Differences among the parties remained,'' the statement said, though ''some common elements'' were seen in ''proposals, suggestions and recommendations'' put forward by all participants and welcomed by the six countries.

The six agreed to hold the fourth round in Beijing by the end of September. They will convene a working-group meeting ''at the earliest possible date'' to ''define the scope, duration and verification as well as corresponding measures for first steps for denuclearization, and as appropriate, make recommendations'' at the next round, the statement said.

Delegation officials said ''first steps'' and ''corresponding measures'' were references to a freeze of nuclear programs and compensation.

The six also agreed to set up an expert group if necessary to help the working group prepare.

The third round effectively continued for six days, including the initial two-day working group meeting.

The six parties ''reaffirmed their commitments to the goal of denuclearization of the Korean Peninsula and stressed the need to take first steps toward that goal as soon as possible,'' the statement said.

Underlining the long and winding road ahead, the six nations also ''stressed the need for a step-by-step process of 'words for words' and 'action for action' in search for a peaceful solution to the nuclear issue.''

The United States, Japan and South Korea have repeatedly called for ''complete, irreversible and verifiable'' dismantlement of all nuclear operations, including use of atomic energy for power. Pyongyang wants to hold on to nuclear programs it says are for energy purposes.

The drafting process for the statement began Friday amid reports that North Korean chief delegate, Vice Foreign Minister Kim Kye Gwan, had threatened in a bilateral meeting with his U.S. counterpart that Pyongyang would conduct nuclear tests if the six-party talks failed to make progress.

Senior U.S. officials played down the North Korean remarks made to Assistant Secretary of State for East Asian and Pacific Affairs James Kelly, saying they did not take the comments as a ''threat.''

On the first day, North Korea and the United States presented proposals for the first time to move the talks forward since the multilateral dialogue was launched last August. Japan and South Korea also offered to conditionally respond to Pyongyang's call for energy aid in exchange for freezing its nuclear programs.

As the talks entered the crucial drafting stage, the North Korean delegation moved to underscore its position Friday night, appearing before reporters for the first time and reading out a statement.

North Korea vowed in the statement to freeze its nuclear facilities and reprocessed plutonium if the United States were to accept three demands -- that Washington joins other countries in providing North Korea with 2,000 megawatts worth of energy aid; remove North Korea from its list of terrorism-sponsoring countries; and lift economic sanctions.

The statement also said Pyongyang is ready to dismantle ''all nuclear weapons programs'' if Washington abandons what North Korea calls a ''hostile policy'' toward the communist state.

The United States proposed a three-month ''preparatory period'' for dismantling North Korea's nuclear programs and offered incentives, including energy aid by the other four countries and a provisional multinational security guarantee, if Pyongyang commits to doing away with the programs.

South Korea's chief delegate, Deputy Foreign Minister Lee Soo Hyuck said he sees the outcome as a ''starting point'' to accelerate the talks, and the concrete proposals put forward by the participants gave ''concrete guidelines for the first time.''

Wang said the United States and North Korea vowed to ''seriously study'' each other's proposals.

Japan's chief delegate Mitoji Yabunaka, head of the Japanese Foreign Ministry's Asian and Oceanian Affairs Bureau, said the six-nation talks ''have come to place where we are in the right ballpark'' as North Korea showed willingness to ''take the first step toward dismantling its nuclear programs.''

The nuclear crisis erupted in October 2002 when the United States said North Korea had admitted to running a secret uranium enrichment program in violation of international agreements, including a 1994 nuclear accord between Washington and Pyongyang.

The 1994 accord, the Agreed Framework, has virtually collapsed since then, with North Korea restarting a mothballed nuclear power station, ejecting International Atomic Energy Agency inspectors from the country, and withdrawing from the Nuclear Non-Proliferation Treaty. ==Kyodo