The agreement, reached after three days of talks, requires North Korea to finish disabling its main nuclear facility by the end of October. Meanwhile the United States, China and the other three nations taking part would complete promised deliveries of fuel oil and other economic aid.
Beyond that, the envoys agreed to a robust verification team of experts who will visit North Korean nuclear facilities, review its documents and interview its technical experts, said a press communique read out by China's envoy, Wu Dawei, at the end of the meeting.
Some specifics of the verification remained to be worked out, but experts and diplomats from the six nations hoped to agree on those steps by early September, said U.S. Assistant Secretary of State Christopher Hill.
"We would like the protocol to be reached within 45 days and secondly to begin verification within 45 days. We're anticipating that and we don't see any obstacles," Hill told reporters after the talks.
The agreement, if not yet complete, signals the start of the final phase of the yearslong on-again, off-again negotiations to get North Korea to abandon its nuclear weapons program.
Beyond the October deadline for disabling North Korea's main facility at Yongbyon, the agreement did not set a timetable for full disarmament. But the administration of U.S. President George W. Bush is believed to be eager to see North Korea disarmed before Bush leaves office in January.
Questions remain about how much of its nuclear programs North Korea disclosed in a declaration last month to the six-party group, which also includes Japan, Russia and South Korea. The North, which exploded a nuclear device in 2006, is believed by experts to have produced enough weapons-grade plutonium to make as many as 10 nuclear bombs, and the U.S. has accused Pyongyang of running a second weapons program based on uranium.
Before the latest talks, poor and energy-starved North Korea complained that other parties had only provided 40 percent of promised fuel aid equivalent to 1 million tons of oil under a February 2007 disarmament deal.
Saturday's agreement outlined specific steps to meet those promises. The United States and Russia pledged to provide the outstanding amount of heavy fuel by the end of October, while China and South Korea would work to sign agreements with North Korea on other assistance, the press statement said.