SEOUL_ An American team of nuclear experts wrapped up a rare trip to North Korea today after surveying the communist country’s main nuclear complex and holding talks with Pyongyang officials to determine how to disable the facilities.

The seven-member delegation returned to Seoul after crossing the tense land border between the two Koreas, said an official at the American Embassy in Seoul, who spoke on condition of anonymity citing department policy. He declined to provide further details.

The trip came amid suspicions about possible North Korean cooperation with Syria on a nuclear facility.

A senior American nuclear official, Andrew Semmel, said yesterday that North Koreans were in Syria and the government in Damascus may have had contacts with “secret suppliers” to obtain nuclear equipment.

Assistant Secretary of State Hill, the chief American nuclear negotiator with North Korea, said such reports are an “important reminder of the need to accelerate the process we’re already engaged in,” referring to the six-nation talks aimed at ridding the North of its nuclear weapons and programs.

“It does not change the goal we are aiming for,” he said.

During a five-day visit, the American experts teamed up with Chinese and Russian specialists to survey the North’s main atomic facilities at Yongbyon, 60 miles north of Pyongyang, in an effort to determine how to disable them so they cannot produce material for bombs.

They also held talks with North Korean officials in Pyongyang. The discussions produced a “detailed plan” on disabling Yongbyon facilities, China’s official Xinhua news agency reported, citing Chu Xuming, the Chinese member of the three-nation team.

The chief Korea expert for the U.S. State Department, Sung Kim, who headed the experts’ group, said Thursday their two-day trip to Yongbyon was useful.

Their findings are to be reported to officials during the six-nation talks, expected to resume in Beijing next week.

North Korea is required to disable Yongbyon in exchange for economic aid and political concessions under a February deal with America, China, Japan, South Korea and Russia. In July, the North closed its sole functioning reactor at Yongbyon and other facilities ahead of their disablement.

Pyongyang agreed at bilateral talks with America earlier this month to complete the disablement by year’s end.

North Korea, which conducted its first-ever nuclear test last October, has been cooperative in the nuclear disarmament talks as Washington made a series of conciliatory moves, including meeting Pyongyang’s demand in a separate banking dispute with America.