New York ? Egypt secretly supplied crucial help — both technology and expert manpower — to the chemical weapons program of Saddam Hussein’s Iraq in the 1980s, U.S. arms investigators have found.

The CIA’s Iraq Survey Group says Egyptian specialists helped the Iraqis make “technological leaps” on poison gas at the height of the Iran-Iraq War, when Baghdad used nerve agents to kill thousands of Iranian soldiers and Iranian and Iraqi civilians.

The U.S. report is the most authoritative and detailed since such collaboration between the Arab nations was first rumored in the late 1980s.

The Cairo government rejected those earlier allegations, and Egypt’s Washington embassy reiterated that denial when asked by The Associated Press about the CIA report. But in AP interviews, United Nations arms inspectors who scoured Iraq’s files and facilities in the 1990s corroborated the U.S. finding.

Like former enemy Israel, Egypt has long been believed to possess chemical weapons.

In 1981, after the outbreak of war with Iran, President Saddam’s Iraqi government paid Egypt $12 million “in return for assistance with production and storage of chemical weapons agents,” the U.S. weapons hunters say in a little-noticed annex of their Comprehensive Report, a 350,000-word document issued last October.

An Iraqi woman holds pictures of victims in this March 16, 2004, file photo at the Halabja memorial hall in Halabja, Iraq, dedicated to the anniversary of the gassing of 5,000 Kurds in the town by Saddam Hussein's regime in 1988.

From 1983 to 1988, the Iraqis repeatedly used mustard gas, tabun, sarin and possibly other chemical agents against the Iranians. Most notoriously, in 1988, Iraqi aircraft dropped sarin and mustard gas on Iranian-held villages in rebellious Iraqi Kurdistan, killing up to 5,000 Iraqi Kurdish civilians.

The Duelfer report says that in the mid-1980s Baghdad had invited Egyptian chemical weapons experts to Iraq to help with production of sarin, a nerve agent that when inhaled can produce symptoms within seconds — convulsions, paralysis, respiratory failure and possibly death.

From 5 tons in 1984, Iraqi sarin production rose to 209 tons in 1987 and 394 tons in 1988, the report says.

The Duelfer findings were unsurprising to experienced U.N. inspectors, who first entered Iraq in 1991 after it was defeated by a U.S.-led coalition in the Gulf War, to destroy its chemical and biological weapons and dismantle its project to build nuclear bombs.