WASHINGTON (AP) _ The United States and South Korea said Wednesday that patience is wearing thin among international negotiators pressing North Korea to hand over a promised declaration of its nuclear weapon efforts.

A spat over the North's declaration, which was due by the end of last year, has deadlocked six-nation nuclear talks. Disarmament negotiators insist that it address claims of a secret uranium enrichment program and allegations that the North transferred nuclear technology to Syria.

"Time and patience is running out," South Korean Foreign Minister Yu Myung-hwan said at a news conference with Secretary of State Condoleezza Rice.

Rice, after a private meeting and lunch with Yu, told reporters that "it is really time now for there to be movement on the declaration."

"We've been at this for quite a long time," she said.

Asked if the Syria allegations were holding up the North providing a list, Rice said the U.S. expects the declaration and "any associated documents" will "show the full range of the North Korean programs and activities."

In an effort to make progress, the U.S. has indicated a willingness to give North Korea some leeway on how to present its declaration, including the possibility of separate documents.

During talks among the Koreas, China, Japan, Russia and the United States in October, the North promised to lay out its long history of nuclear weapons development in a formal declaration by the end of 2007, a step toward eventually giving up its atomic bombs and the means to make them. In exchange, North Korea was to receive aid and political concessions, including its removal from U.S. terrorism and sanctions blacklists.

North Korea says it gave the U.S. a list of its nuclear programs in November. The Bush administration says it never received a "complete and correct" list.

The chief U.S. envoy at the disarmament talks, Christopher Hill, said Tuesday that back-channel diplomatic discussions with North Korean officials could break the impasse in negotiations. He provided no details.

North Korea has insisted it does not have an active uranium program. It also denies accusations it spreads its nuclear expertise beyond its borders.

Yu also said that he and Rice mapped out details for a mid-April summit between newly elected conservative President Lee Myung-bak and President Bush at the Camp David presidential retreat in Maryland.

Lee, who took office last month, has steered his government's North Korea policy away from the path favored during the past decade of liberal governments, which were reluctant to publicly criticize North Korea. Lee has promised a tougher stance in dealing with South Korea's impoverished neighbor.

Copyright 2008 The Associated Press.