Police combed streets and detained an Iraqi and Iranian after a warning that Palestinian terrorists were planning to bomb a U.S. air base, officials said Saturday.

Authorities also picked up an off-duty American soldier and an Australian tourist whose beards led authorities to mistake them for Palestinians. Both men were released after an identity check, the officials said.The roundups came Friday and Saturday after Philippine officials said they received a warning that Palestinians planned to bomb Clark Air Base and bars frequented by American servicemen during the weekend.

Police said they received a report from the Israeli secret service Mossad that the bombings were to be carried out by at least eight Palestinians. But the U.S. and Israeli embassies in Manila said they had no knowledge of such a warning.

Despite the stepped-up patrols of Philippine authorities, U.S. and Filipino troops guarding the sprawling U.S. base took no special security measures that were visible.

Officials at Clark could not be contacted for comment. But base spokesman Maj. Thomas Boyd appeared Saturday on the U.S. military's Far East Network and warned the American military community to be on the alert for bomb attacks.

Boyd made no reference to a Palestinian threat, but he urged service members and families to be on the lookout for unattended packages in restaurants and other public places.

In October, American authorities stepped up security at Clark, Subic Naval Base and four smaller U.S. installations after communist rebels killed three Americans and a Filipino near Clark.

Also Saturday, in Manila, 50 miles to south of Clark, U.S. Ambassador Nicholas Platt cautioned the Philippine government against ending the lease on U.S. military bases.

In a speech to American and Filipino war veterans, Platt asked, "Does the Philippines wish the United States to continue to share the burden of Philippine defense?"

Platt said that in exchange for the bases, the United States guarantees the Philippines' defense against external aggression. He said the arrangement enables the 160,000-member Filipino army to concentrate on fighting the country's 20-year communist insurgency.

U.S. and Philippine officials began early this month to review the 1947 agreement under which the United States operates military bases in the country. The lease expires in 1991.

In Angeles City, police and soldiers immediately stepped up patrols after receiving the warning Thursday. Police chief Lt. Col. Orlando Macaspac said he had set up checkpoints to inspect vehicles entering the city. He said he had also posted operatives at hotels, restaurants and bars.