Yasser Arafat, the chairman of the Palestine Liberation Organization, said early today that U.S. tanker aircraft helped refuel the Israeli Air Force planes that attacked his personal headquarters near here Tuesday.

The PLO leader also said at a news conference that he had left his headquarters to go jogging on the beach only 15 minutes before the Israeli aircraft leveled the complex with bombs and air-to-ground missiles.

Looking relaxed and exuding confidence, Arafat said that he knew which U.S. base in the Mediterranean was involved in supplying the tankers but would name it only "at the appropriate time." He declined to explain why he would not name the base now.

Quoting from the authoritative British International Institute of Strategic Studies, he contended that Israel does not own enough tanker aircraft to have conducted the raid without "strategic and operational coordination" with the United States.

He said that eight fighter-bombers escorted the refueling aircraft in addition to the eight that carried out the attack against his Bordj Cedria headquarters complex.

Arguing that the U.S aircraft that he alleged were involved had been lent as "part of the strategic agreement between Israel and America," Arafat asked: "Can you explain how more than 20 aircraft stay in the air for more than seven hours from takeoff to landing, refueling" twice on the way to target, once headed home?

"Do you want to convince me that the U.S. 6th Fleet has not felt the existence of these planes in the air for seven hours?" Arafat asked. "The Americans cannot say they didn't know."

Asserting that Israeli officials had said they informed the Americans of the planned raid ahead of time, he accused the administration and President Reagan himself of accepting the attempted assassination of the PLO chairman, although "this chairman was one who signed the Jordan-PLO peace initiative."

Denouncing the alleged American collusion and Reagan's implied endorsement of the raid as "absolutely shameful," Arafat said the Americans were "bombing the peace process."

Yesterday, Tunisian Army engineers used bulldozers, pickaxes and shovels to sift through the wreckage. They recovered a human hand and a foot from the building housing Force 17 guards. Palestinian sources said they feared as many as 27 persons were buried in the rubble of Arafat's headquarters buildings, including 17 Palestinians held in basement cells for disciplinary reasons.