North Korea agreed to disable its main reactor by the end of October and allow international inspections to verify its nuclear disarmament in a deal reached Saturday at the end of six-nation talks.

In exchange, the United States, China, and three other countries would complete promised deliveries of fuel oil and other economic aid to Pyongyang.

The agreement, reached after three days of talks, opens the final phase of long and tortuous efforts to rid North Korea of its nuclear weapons.

"The parties reach an important consensus," said China's envoy, Wu Dawei, as he read out the group's press communique at the end of the meeting.

The envoys from the six nations — which also included South Korea, Japan, and Russia — agreed that a verification procedure would include a team of experts who will visit North Korean nuclear facilities, review its documents and interview its technical experts.

The agreement also allows the nuclear inspectors to call on the expertise of the International Atomic Energy Agency to help in verification.

Technical details of the verification process still need to be hashed out by a working group, but the six nations hope to agree on specific 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 envoys will be gathering later in the month for a regional security forum in Singapore and may hold informal talks there, he said.

The agreement, though not yet complete, signals the start of the final phase of years of 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 nuclear facility at Yongbyon, the agreement did not set a timetable for full disarmament. But the Bush administration is believed to be eager to see North Korea disarmed before he leaves office in January.

Kim Sook, Seoul's top nuclear envoy, said afterward that "a very difficult task" lies ahead in implementing verification, though he did not elaborate. He added there should be "unlimited" access to the North's facilities during the verification process.

Questions remain about how much of its nuclear programs North Korea disclosed in a declaration last month. 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 statement said.

Japan — which has opted out of contributing because of lingering friction with North Korea over abductions of Japanese citizens in the 1970s and '80s — agreed to pitch in too "as soon as possible when the environment is in place."

Earlier Saturday, the U.S. envoy said negotiators wanted verification measures of the kind used in other countries.

"We're not asking for anything unusual. We're asking for things that are done all over the world. We want a basically standard kind of package on how you verify this type of nuclear program," Hill said.

In response to North Korea's nuclear declaration, the United States announced it would remove the country from a list of state sponsors of terrorism and relax some economic sanctions against it. Normally reclusive North Korea blew up the cooling tower at Yongbyon and allowed TV broadcasts of the event.

The steps paved the way for the resumption of the six-nation meetings in Beijing. Those talks had been on hold since last October.

The nuclear standoff began in late 2002 when the U.S. accused North Korea of seeking to secretly enrich uranium in violation of a 1994 disarmament deal.