The U.N. nuclear watchdog agency has found that Taiwan's experiments with plutonium extended up to the mid-1980s, diplomats said Wednesday, uncovering a key detail about the country's now-abandoned nuclear weapons program.

It had been known that Taiwan (search) briefly revived its nuclear weapons research program in the 1980s, and the revelations confirm suspicions that plutonium separation experiments were carried out at that time.

Taiwan first launched its nuclear weapons program in the 1960s, but suspended in the following decade under pressure from the United States, which apparently feared the response from Taiwan's rival China.

Taiwan's governent has never acknowledged having a secret weapons program, according to analysts.

The experiments were uncovered in inspections and testing conducted by the International Atomic Energy Agency (search) after the Taiwanese government agreed to voluntary extra controls on the country's peaceful nuclear program, the diplomats said.

The diplomats told The Associated Press that their information was based on preliminary samples taken in Taiwan by IAEA inspectors indicating that plutonium separation experiments probably continued until about 20 years ago.

The diplomats, who are familiar with the IAEA, spoke on condition of anonymity. Officials at the Vienna-based IAEA said they would not comment.

One of the diplomats cautioned against drawing parallels between Taiwan and South Korea, whose government recently acknowledged that its scientists once dabbled in extracting plutonium and enriching uranium — both of which can be used to make nuclear arms.

While the South Korean revelations reflected continued secret weapons-related research, it was common knowledge that Taiwan had engaged in nuclear weapons research after China exploded its first bomb in the 1960s, the diplomat said.

What the agency now was trying to do was to flesh out details of the Taiwanese program, with environmental sampling and other methods, he said.

The agency was not expecting to find new experiments with possible weapons applications beyond the mid-1980s, said the diplomat. "But there will be new things they did not discover in the past" about the previously known program because of the extra access Taiwan was now granting agency inspectors, he said.

In Taipei, Taiwan, Foreign Ministry spokesman Michel Lu said that ministry was not aware of the reports and would not immediately comment on them. Officials at Taiwan's Atomic Energy Council were not available after business hours Wednesday.

Andrew Yang, a defense analyst at the Chinese Council of Advanced Policy Studies (search), a Taipei think tank, said that it has long been common knowledge in Taiwan that the island's nuclear scientists were working on a bomb in the 1970s and 1980s.

Yang said the work was done at the Chung Shan Institute (search), the military's biggest research center. He said the government has yet to publicly confirm the project existed.

"I don't think they got anywhere close to building a nuclear device," Yang said. "But they did have the technology and the know-how."

The program was shut down and U.S. officials sealed off the laboratories and test sites in 1988 shortly after a military officer involved in the project, Chang Hsien-yi, defected to the United States with computer information about the program.

Taiwan's nuclear weapons program has been the subject of numerous media reports and books.

Jay Taylor, a former Asia specialist in the U.S. Foreign Service, wrote in his biography of the late Taiwanese President Chiang Ching-kuo, who took overall responsibility for the secret nuclear project, that the CIA recruited Chang to gather information about the program.

The project was approved by the late President Chiang Kai-shek (search), Ching-kuo's father. The elder Chiang in 1965 ordered that the nuclear bomb study move from research to development, the book said.

The CIA estimated in 1974 that Taiwan would be ready to build a nuclear weapon in "five years or so," according to Taylor's book, "The Generalissimo's Son," published in 2000.

In 1976, IAEA inspectors found that 10 barrels of used fuel containing about 1 pound of plutonium were missing.

The Washington Post cited official U.S. sources in an Aug. 29, 1976, report that said Taiwan had been secretly reprocessing for some time and had been producing plutonium for a nuclear weapon. The same article said that Washington demanded Chiang Ching-kuo dismantle the reprocessing facility and ship back related equipment to the United States.

Chiang accepted the U.S. demands and asserted that Taiwan had no intention to develop nuclear weapons. He issued a statement on Jan. 23, 1977, supporting President Jimmy Carter's call for a total ban on nuclear testing.

Taylor writes that "privately, Ching-kuo ordered the reprocessing program put on hold for the time being but for research work to continue."