BAGHDAD, IRAQ, OCT. 14 -- Iraq has turned off its air-defense radar to prevent U.S. reconnaissance planes from monitoring the signals and using the information to program U.S. electronic warfare equipment, according to knowledgeable diplomatic sources.

The step was taken several weeks ago despite the danger of war in the region but appears intended to diminish chances that the United States can develop ways to jam the warning and guidance systems of Iraq's Soviet- and French-made ground-to-air missiles, the sources said.

Diplomatic sources here also disclosed another indication of Iraqi concern about the risks of war. They said Iraqi President Saddam Hussein's government has urged the United States to resume contacts between U.S. and Iraqi military experts to prevent accidental air or sea clashes in the Persian Gulf region that could lead to war. But the sources said a proposal to that effect, relayed to Washington on Aug. 21, has gone without a response.

Iraq's move on radar defenses may be in part to avoid a repetition of Syria's experience during the 1982 Lebanon war. Israeli warplanes scored a lopsided victory against the Syrian air force then, largely because electronic jamming, prepared with information gathered by reconnaissance drones, quickly disabled most of the ground-to-air missiles that constituted the bulk of Syria's air- defense systems.

Apparently seeking a similar advantage, U.S. reconnaissance planes have been monitoring Iraq's radar and ground-to-air missile arsenal closely as part of the multinational military buildup in the gulf that began after Iraq's Aug. 2 invasion of Kuwait, the sources said. U.S. officials have said repeatedly that they would rely heavily on air strikes, including electronic jamming of Iraqi missile systems, if fighting were to break out.

Baghdad's military authorities decided that their radar systems could be turned back on swiftly enough to defend against an attack, but that in the meantime U.S. forces would have less opportunity to study their characteristics and perfect an electronic jamming strategy, one informed source said.

Another source suggested, however, that the Iraqi military is altering its air defense systems during the shutdown in hopes of making them more difficult to read by U.S. electronic reconnaissance.

The measure is the second recent indication of increased Iraqi concern about U.S. access to information on Iraq's air defenses. A military spokesman warned Friday that Soviet nationals could be prevented from leaving Iraq if Moscow feeds Iraqi military secrets to the United States during a planned visit to Moscow this week by Defense Secretary Richard B. Cheney.

The Soviet Union, which has been Iraq's largest arms supplier, is believed to have accumulated a wealth of information on Iraq's military establishment. Large-scale weapons sales, framed by a 1972 treaty, meant a number of Soviet military advisers have been working within the Iraqi military with access to defense secrets.

The number of Soviet military advisers has dropped from between 200 and 300 before the gulf crisis to fewer than 100 as of last week, according to the Moscow newspaper Izvestia. The United States has urged Moscow to withdraw them all in a display of solidarity with the Western and Arab nations aligned against Iraq in Saudi Arabia and the Persian Gulf.

Tensions in the gulf and the large deployment of U.S. forces there apparently motivated Iraq's Aug. 21 request for renewed contacts with the United States to prevent accidental air or naval clashes in the region. The risk that warfare might erupt in the gulf because of an accident has been cited by Arab officials as their worst nightmare.

The United States and Iraq conducted regular consultations on their military activities in the gulf under an agreement dated Aug. 16, 1987, three months after an Iraqi warplane armed with French-made Exocet missiles attacked a U.S. Navy ship, the Stark, during the Iran-Iraq war. Baghdad later apologized for the attack, which killed 37 sailors, and said it was an accident.

These consultations were canceled, however, after Iraq's invasion of Kuwait brought about the U.S. military buildup in and around Saudi Arabia. Instead, Washington sent a note to the Iraqi government Aug. 15 warning that U.S. forces were escalating activities around the gulf and would respond to any move by Iraqi warplanes or ships that was judged threatening.

The note warned Iraqi planes and ships to stay clear of U.S. forces in the region and declared that any move by an Iraqi plane to lock onto U.S. aircraft with radar would bring a response, the sources said. Locking onto enemy aircraft with radar could be considered a first step toward firing a missile.

In response, Iraq sent Washington the Aug. 21 note, listing similar warnings about U.S. forces and the need for them to stay away from Iraqi forces, the sources said. But the Iraqi note also proposed the experts' meeting to avoid an unwanted conflict resulting from an accident.

News services added the following:

Iraq said Sunday that it had nothing to do with the assassination of Egypt's Parliamentary Speaker Rifaat Mahgoub, Reuter reported from Baghdad.

The Iraqi News Agency quoted its Arab affairs editor as saying charges of involvement by the Egyptian media were propaganda "based on lies and changing facts."

Egypt has not officially accused anyone of Friday's killing, but the Interior Ministry said it was carried out by a team from outside the country, Reuter said.

In Cairo, newspapers reported that police have rounded up dozens of Moslem extremists and foreigners suspected of involvement in the slaying, including 25 Palestinians and Iraqis, according to the Associated Press.