The head of a U.N. committee monitoring an arms embargo on Angola appealed today to the world's top intelligence agencies to help crack down on the illicit Angolan arms and diamond trade.

Robert Fowler, Canada's ambassador to the United Nations, said the Angolan diamond industry has helped fuel decades of civil war in the former Portuguese colony, supplying the rebel force known as UNITA with money to purchase arms in violation of a six-year-old embargo. He named two panels of international experts to track sanctions violations.

"I don't think the tap can be turned off," said Fowler, who chairs a Security Council committee set up to monitor the sanctions on Angola. "But let's force them into the gray markets and the black markets. Let's force them to use more unscrupulous middlemen, so that the amount of money they get to buy tanks is less."

Fowler's appeal is unusual because it openly invites foreign intelligence agencies and the International Criminal Police Organization, or Interpol, to help the Security Council enforce U.N. sanctions. The United Nations is usually reluctant to be associated with foreign intelligence agencies, particularly in light of the revelations this year that the United States and other countries used U.N. weapons inspection teams as cover for spying on Iraq.

The United States, which armed and trained UNITA's forces during the Cold War, has agreed to share intelligence with the United Nations to help identify sanctions violators and senior UNITA officials subject to the U.N. embargo, officials said. Washington is also considering providing financial support to the panel.

"The United States . . . stands ready to work together with any state committed to the common goal of improved implementation of the U.N. sanctions against UNITA," said Peter Burleigh, the acting U.S. representative to the United Nations.

Fighting between UNITA--the National Union for the Total Independence of Angola--and Angola's ruling Popular Movement for the Liberation of Angola has raged since before the country's independence in 1975. The United States and South Africa backed UNITA and its leader, Jonas Savimbi, in its fight against the then-Marxist ruling party and its Cuban and Soviet allies until a 1991 peace accord that set up elections the following year.

But Savimbi refused to accept defeat in the September 1992 vote, the nation returned to war and the Security Council imposed sanctions on UNITA in 1993. A peace deal in 1994 collapsed last year, and Angola returned to full-scale war.

A U.N. report estimates that the rebel leader has earned $3 billion to $4 billion from the diamond trade. Fowler said there were indications that Savimbi had also profited handsomely from investments.

The investigative panels will track financial records of arms and diamond merchants suspected of trading with UNITA and pressure governments to stop aiding the illicit trade.