Negotiations over North Korea's nuclear-weapons programs have been extended to a seventh day in the Chinese capital. Delegates of six nations are trying to resolve differences over a statement of principles to lay the ground rules for future negotiations on the North's nuclear disarmament. .

Delegates had hoped to wrap up discussions, but with differences persisting over the latest draft prepared by China, they decided to keep talking through Monday.

Sunday's meetings were brief, and appeared to produce no breakthroughs.

U.S. envoy, Christopher Hill, described differences the six nations have on the general terms for North Korea's nuclear disarmament.

"We agree with what we're trying to do," he said. "The issue is how we express that in this document. Some delegations prefer to leave some things more ambiguous. My delegation would like to see things less ambiguous."

Talks are stalemated over North Korea's demand for others to fund a light-water reactor for electricity, a request Washington rejects due to concerns that Pyongyang might use the reactors to make atomic weapons.

Russia's chief delegate on Friday said the draft proposed by China Friday contains language on North Korea's right to have a civilian nuclear program.

Russia, South Korea, and China have all recently broken ranks with the United States and Japan over this issue - which North Korea has only brought up in this latest round of talks.

The negotiations resumed last Tuesday after a 37-day recess in which North Korea was supposed to review an earlier draft. That document, also prepared by the Chinese, contained offers of massive non-nuclear energy, economic assistance, and security guarantees for the impoverished communist nation.

Three earlier rounds held since 2003 have failed to produce a concrete agreement for North Korea to dismantle its nuclear programs.