Hamas and Fatah appeared to be on the verge of a major confrontation on Sunday as representatives of the two sides stepped up their war of words over a controversial document drafted by some Palestinian prisoners held in Israeli jails. Hamas officials on Sunday accused Palestinian Authority Chairman Mahmoud Abbas and his Fatah party of planning a "bloodless coup" to topple the Hamas government and said his proposed referendum was "illegal." The tensions come as Abbas's 10-day ultimatum to Hamas to accept the document or else he would call a referendum is due to expire on Monday night. At least six people were injured in clashes that erupted in Rafah early Sunday morning between Hamas and Fatah gunmen. In a move that has been strongly condemned by Hamas, Fatah announced on Sunday that it would deploy 1,250 gunmen in the Gaza Strip. The move follows the deployment of some 2,500 Fatah gunmen in the Jenin area over the weekend. Fatah leaders, meanwhile, stressed that Abbas was determined to hold the referendum "at any price" and suggested that the countdown for the collapse of the Hamas government had begun. "The Palestinian Basic Law does not allow holding any referendum in the Palestinian territories," PA Prime Minister Ismail Haniyeh told reporters after visiting the Finance Ministry in Gaza City. "The political situation also does not allow for such a referendum because we just had parliamentary elections a few months ago. The issue of the referendum is therefore not so easy." Hamas spokesman Sami Abu Zuhri launched a scathing attack on Abbas and Fatah, accusing them of plotting to bring down the Hamas government through a "bloodless coup." Referring to the current round of "national dialogue" talks between Hamas and Fatah, Abu Zuhri said: "These talks are a real circus because one side is trying to impose its will on the other." Aziz Dweik, speaker of the Hamas-dominated Palestinian Legislative Council, accused Abbas of trying to blackmail the Palestinians through his planned referendum. Dweik met on Saturday night with Abbas in Ramallah and tried to persuade him to abandon the idea of the referendum, but to no avail. "This referendum is aimed at blackmailing the Palestinians," he told reporters. "It's telling the Palestinians that they either accept the document or face starvation. This is illegal and undemocratic." Azzam al-Ahmed, a Fatah legislator and advisor to Abbas, dismissed claims that the referendum was illegal and called on the Hamas government to resign immediately. "If the government respects itself, it should resign before it is sacked," he told a news conference in Ramallah. "Hamas does not have a right to veto the [prisoners'] document and we're not going to wait for their approval. Who do they think they are? They must remember that Palestine is greater than them and their movement. They don't want to reach any understandings or agreements over the referendum. They only want to issue statements and deliver speeches at the mosques." The Fatah official said that unless an agreement is reached in the next few hours, Abbas would issue a "presidential decree" on Tuesday morning calling for holding the referendum within 40 days. "President Abbas alone will decide about when to hold the referendum," he argued. "The prime minister's job is to help the president. This is what the law stipulates and it's time for Haniyeh to return to his senses." Another Fatah official, Ahmed Abdel Rahman, expressed doubt that Hamas would be able to remain in power as long as its leaders remained opposed to the prisoner's document, which calls, among other things, for the creation of a Palestinian state in the West Bank, Gaza Strip and east Jerusalem. "Hamas can't remain in power as long as it challenges international, Arab and Palestinian resolutions," he said. "The majority of the Palestinians support the document. The situation in the Palestinian areas is deteriorating on a daily basis."