As deadly internecine Palestinian violence continued on Thursday, Palestinian Authority President Mahmoud Abbas issued a dramatic ultimatum to Hamas: give up the fight for "all of Palestine" within 10 days, or face a referendum on a range of negotiation policies put forward in a recent document. Accepting this document, which was drafted by Palestinian security prisoners earlier this month and which calls for the establishment of a Palestinian state within the 1967 boundaries, would effectively mean that Hamas would relinquish its demand to "liberate all of Palestine." The document does not refer specifically to Israel's right to exist and calls for pursuing attacks on Israelis in the West Bank and Gaza Strip. To view a summary of the document Abbas may call to referendum click here. Abbas was speaking at the beginning of a two-day "national dialogue" conference aimed at easing tensions between Hamas and Fatah and avoiding civil war. In Gaza City, however, those tensions continued, as at least one person was killed and 15 others were wounded, some seriously, in fierce clashes that erupted between Hamas militiamen and security officers belonging to the Palestinian Authority's Preventive Security Force. Eyewitnesses said the members of Hamas's new "back-up" security force exchanged gunfire for several hours with the PA officers near the Palestinian Legislative Council and government offices in Gaza City. Later, two members of Abbas's Force 17 presidential guard were shot and seriously wounded by Hamas gunmen. At the dialogue conference, Abbas surprised representatives of various Palestinian factions attending the parley through a video-conference link between Ramallah and Gaza City by warning that he would seek a referendum if Hamas refuses to accept the prisoners' document, which also calls for the formation of a national unity government. Abbas's ultimatum is likely to increase tensions with Hamas. Analysts here said they did not see how such a referendum could be held without the backing of the Hamas government and the Hamas-dominated parliament. Many Hamas leaders expressed reservations about Abbas's planned referendum, saying it was "premature" to talk about such a move even before the dialogue has ended. However, some Hamas spokesman said they were not opposed to the principle of holding a referendum. Addressing Hamas leaders, Abbas said: "If you don't agree, then I will say that frankly none of us will be responsible, and in 40 days I will call for a referendum. I will ask my people directly whether they accept or do not accept this plan." He added: "The homeland is in danger and we can't wait. Today rallies and dialogues end and as of tomorrow the countdown will begin. We must not resort to arms, because Palestinian blood is sacred." Abbas criticized Israel for its ongoing military operations, referring specifically to the killing of four Palestinians during an IDF raid in Ramallah on Wednesday. "These attacks are continuing and no one is moving to stop them," he said. "[Israeli] missiles are falling all the time on the Gaza Strip and the internal fighting has only aggravated matters." Abbas said most Palestinians agreed on the need for an Israeli withdrawal to the pre-1967 borders. "We will not accept placing one stone in the Palestinian territories occupied in 1967, and will not allow anyone to determine our fate," he said, referring to the construction of settlements and Prime Minister Ehud Olmert's "convergence" plan. "We want a Palestinian state with Jerusalem as the capital and a just solution to the issue of refugees." Hamas legislator Salah Bardaweel expressed "astonishment" at Abbas's ultimatum, saying his movement was "disturbed" by the idea. "Have we concluded the national dialogue to be able to talk about a referendum?" he asked. "The prisoners' document is only one of several ideas that this conference will discuss." Bardaweel also accused Abbas of manipulating the prisoners' plight for political purposes. "This is a very emotional issue and we must relate to the prisoners more seriously," he added. Ghazi Hamad, spokesman for the Hamas cabinet, also expressed reservations about the referendum. "We hope to resolve our differences without the need for a referendum," he said. "We're not against the will of the people, but the referendum should not be an alternative to dialogue. We're also not opposed to the establishment of a Palestinian state within the 1967 borders." Hamas spokesman Sami Abu Zuhri accused Abbas of trying to pressure the Hamas government into accepting a different policy. He said the referendum was aimed at "bypassing" the choice of the majority of the Palestinians who voted for Hamas because of its political program. "Why is he trying today to bypass the Palestinian Legislative Council by going to a referendum?" he asked. "This did not happen in the past." Ziad Dayyeh, a top Hamas representative in the Gaza Strip, said his movement was totally opposed to the prisoners' document because it recognized Israel's right to exist. "We eject any document that includes recognition of the Zionist entity and gives up one inch of Palestinian land," he said. "This is completely unacceptable and non-negotiable." Prime Minister Ismail Haniyeh, addressing the conference from Gaza City, did not comment on Abbas's threat. He said the "area of agreement in political vision [between Fatah and Hamas] is very close," adding, "We affirm our position to unify our political vision, because it will give us the confidence of our people." Fatah legislator and former minister Muhammed Dahlan said his party may agree to join a coalition government if Hamas recognizes the PLO as the sole and legitimate representative of all Palestinians. "If Hamas recognizes the PLO, then Hamas will end its isolation and avoid internal Palestinian fighting," he said. "Hamas's short experience in governing shows that a single party can't succeed in leading the Palestinian people." In Israel, neither the Prime Minister's Office nor the Foreign Ministry were willing to issue a formal reaction to Abbas's proposal on Thursday, with one official saying that any formal Israeli comment at this time would be "counterproductive." However, one official did express satisfaction that Abbas finally seemed intent on exercising his "constitutional authority" to change the situation inside the PA, but added that in the end Abbas would be judged not by his declarations, but rather by whether he followed through and took action. Herb Keinon contributed to this report.