SPECIAL REPORT: GAZA UPHEAVAL The Palestinian Authority and Hamas traded accusations over the weekend following an explosion in the Jabalya refugee camp that killed 19 people and injured more than 120. PA officials held Hamas responsible for the explosion, which took place on Friday evening during a Hamas rally to celebrate the Israeli withdrawal from the Gaza Strip. Hamas leaders in the Gaza Strip, however, claimed Israel was behind the explosion and vowed to resume attacks on Israeli targets. Palestinian Authority Chairman Mahmoud Abbas on Saturday blamed Hamas for the explosion. Addressing thousands of supporters in Ramallah, Abbas said, "I greet you today in these moments of sadness and anger that spoiled our happiness and joy over the departure of the Israeli settlers and soldiers [from the Gaza Strip], I'm shocked and pained by the massacre that occurred in Gaza. May God have mercy on the souls of the martyrs. What happened yesterday is what we always feared would happen, and what we always warned against." "Today, we are required more than ever to end this tragedy that resulted from chaos and military parades in residential areas, undermining the rule of law." Abbas said that the only solution to the conflict would be a full Israeli withdrawal to the pre-1967 borders including Jerusalem, and solving the refugees' problem on the basis of United Nations resolution 194. "A comprehensive solution, and not a partial one, is the only way out," he said. "The withdrawal from the Gaza Strip would be incomplete without a full withdrawal from all the territories that were occupied in 1967." He reiterated his opposition to the idea of establishing a Palestinian state with temporary borders in the Gaza Strip and said all Palestinians were entitled to participate in the parliamentary elections scheduled for next January. "We won't succumb to dictates and provocations from anyone," he said, referring to Prime Minister Ariel Sharon's opposition to the participation of Hamas in the vote. "No one can impose a veto on us." The ruling Fatah party also issued a statement in Gaza City condemning Hamas for holding paramilitary rallies in residential areas. "This rally was held despite our warnings to refrain from displaying and storing weapons in residential areas," the statement said. "The Fatah central committee holds Hamas fully responsible for the deaths that occurred during the military rally [in Jabalya]." However, other Fatah groups in the Gaza Strip rejected the charges against Hamas and accused Israel of standing behind the explosion. In addition, Fatah's armed wing, Aksa Martyrs Brigades, distributed leaflets accusing PA Interior Ministry Gen. Nasser Youssef, who is in charge of security, of "high treason and collusion" with Israel. "It's clear to us that Israel is behind the massacre in Jabalya and our response will be painful," the group said. Prime Minister Ahmed Qurei refrained from voicing criticism against Hamas. "The situation is very dangerous and Israel bears full responsibility for this deterioration," he told reporters in Ramallah. "We urge the international community to interfere to put an end to the Israeli escalation." The Interior Ministry issued several statements strongly condemning Hamas for organizing such rallies in populated areas and dismissed Hamas's claim that Israel was behind the explosion as "untrue." "The explosion occurred when a Hamas vehicle loaded with locally made rockets blew up during the rally," said Interior Ministry spokesman Tawkif Abu Khoussa. He pointed out that a similar explosion in Gaza City last month had killed five Palestinians. "Then, Hamas also claimed that the blast was the result of an Israeli air strike but our investigations showed that this was not the case," he said. "We urge our brothers in Hamas to assume their responsibilities instead of leveling charges against others." The charges drew sharp criticism from Hamas, whose leaders accused the PA of covering up for Israeli "crimes." Hamas leader Mahmoud Zahar accused the PA of waging a "propaganda war" against his movement, insisting that Israel was responsible for the explosion. Dubbing the PA Interior Ministry the "devil's advocate," Zahar accused PA officials of parroting Israeli statements. "On what basis is the Interior Ministry making its claims?" he asked. "Has there been an investigation into the explosion? Did they send anyone to the area to check? Are they just guessing or did they know something in advance?" Zahar pointed out that the PA was addressing Hamas with two different languages. "On the one hand, the Interior Ministry is talking about confiscating the weapons of the Palestinian resistance groups," he said. "On the other hand, Abbas is denying this, saying there has been no talk about this matter. How can we believe the Interior Ministry when the head of the PA is telling us different things? Who does the Interior Ministry represent?" The Hamas leader argued that his movement did not use real explosives or rockets during the rally. "We have removed metal parts from the bodies of some of the victims that prove that the explosion was caused by a missile fired from Israeli helicopters that were hovering over the area at the time," he claimed. Zahar said the explosion was in the context of Sharon's campaign to prevent Hamas from participating in next January's parliamentary election. Although Hamas has threatened to retaliate for the explosion, the movement's leaders stopped short of declaring an end to the unofficial truce with Israel, known as tahdiyah [calm]. Sources in the Gaza Strip said Hamas was not interested at this stage in an all-out confrontation with Israel for fear that renewed violence could harm its chances of running in the parliamentary elections.