RAMALLAH ø The Palestinian Authority warned the United States that it could no longer rely on Palestinian security agencies.

PA sources said the State Department and the U.S. embassy in Tel Aviv were told that Palestinian security agencies have been infiltrated by anti-U.S. insurgency groups. The sources said Washington was warned that any message to PA security agencies would probably be relayed to or intercepted by insurgents.

The PA warning to the United States was relayed in September 2003 by then-PA Security Minister Mohammed Dahlan, Middle East Newsline reported. The sources said Dahlan urged the U.S. embassy and State Department not to relay any requests of plans to visit the Gaza Strip through PA security agencies, particularly the Preventive Security Apparatus, because such information could be forwarded to insurgency groups.

But the sources said the United States ignored Dahlan's appeal. They said that in October the U.S. embassy faxed the PSA with a schedule for the arrival of a U.S. diplomatic convoy the following day.

On Oct. 15, a roadside bomb ripped apart a vehicle in a U.S. embassy convoy that was transporting American visitors to the Gaza Strip. Three U.S. security staff members were killed and one was injured. So far, nobody has been convicted for the attack.

"Dahlan was honest with the Americans," a Palestinian source said. "He said, 'Don't send any faxes to me or my office. If you need something, call.' The Americans just ignored this and this was the consequences."

The Palestinian sources were responding to a U.S. determination that a Fatah carried out the attack on the U.S. diplomatic convoy in a plan approved by PA Chairman Yasser Arafat. The sources did not confirm that Arafat was involved in the strike, but agreed with the U.S. assessment that the Palestinian attackers had high-level access to the PSA.

Since the October 2003 attack, senior U.S. officials have not entered the Gaza Strip, the sources said. They said the United States has warned the PA that Washington would not help any effort to stabilize the Gaza Strip after a planned Israeli withdrawal unless the killers of the Americans were captured and brought to justice.

U.S. diplomatic sources said Arafat agreed to a proposal relayed by an aide for the Palestinians to "pass a message" to the United States. They said a senior Arafat aide and member of the Fatah Central Committee left Gaza City for Arafat's headquarters in Ramallah in September 2003 to seek approval for a Palestinian attack on U.S. interests in the area. The Fatah official, described as a liasion between Arafat and Palestinian insurgents in the Gaza Strip, complained of U.S. policy toward the PA and Arabs.

During their meeting, the sources said, the official asked Arafat whether it was time to relay a message to the United States. Arafat was said to have replied, "May God bless this," which translated into "Go ahead," the sources said.

Soon after the meeting with Arafat, the sources said, Dahlan warned the United States that PA security agencies had been infiltrated by Fatah insurgents. The sources said they did not know whether Dahlan knew of the Fatah plot to attack U.S. interests in the Gaza Strip.

But the sources said the U.S. determination has not changed Bush administration policy toward Arafat or the PLO. On Wednesday, President George Bush ordered another waiver of U.S. sanctions on the PLO to allow its office to continue to operate in Washington for another six months. Bush determined the waiver was required for U.S. national security interests.