Palestinian Authority Chairman Mahmoud Abbas said Saturday he would use his "constitutional powers" against the new Hamas cabinet unless it altered its political program and honored all agreements with Israel. The warning was yet another indication of the growing tensions between Hamas and Fatah in the aftermath of the Islamic movement's landslide victory in January's parliamentary election. The latest crisis came as Hamas prepared to seek the approval of the Palestinian Legislative Council for its new cabinet. The PLC is expected to meet on Monday for a vote on the 24-member cabinet, which is comprised solely of Hamas members. Hamas officials dismissed the warning as "undemocratic," saying it contradicted the will of the majority of the Palestinians who voted for the Islamic movement in the election. Abbas's threat was included in a strongly-worded letter he sent to Palestinian Prime Minister-designate Ismail Haniyeh, said Tayeb Abdel Rahim, secretary-general of the PA. "The president, having conducted a thorough study of the new cabinet's program, has sent a letter to Haniyeh before the vote of confidence in the PLC," Abdel Rahim said at a press conference here. "The president expressed deep regret because the cabinet's program does not take into consideration the main points that appeared in his letter of appointment [to Haniyeh]. The president stressed that the democratic choice does not authorize [Hamas] to overturn the political and legal commitments of the Palestinian Authority and the PLO." Abbas made it clear in his letter that he would go ahead with presenting the cabinet to the PLC for a vote of confidence only if Hamas agreed to change its political program, he added. According to Abdel Rahim, the letter warned that unless Hamas changed its program, the Palestinians would face international sanctions, a move which, he added, would provide Israel with an excuse not to honor its commitments and to pursue its policy of land grabs by imposing its own solutions and drawing its borders unilaterally. "President Abbas will use his constitutional and legal powers if the new cabinet's policies have negative repercussions that could harm the higher national interests of our people," he cautioned. "He will closely follow the performance of the cabinet on the basis of the mandate he received from the people and on the basis of his powers to defend the interests of the people." Abdel Rahim said Abbas's specific demands included recognition of the PLO as the sole, legitimate representative of the Palestinians, as well as recognition of the PA's Basic Law and "Declaration of Independence." Top PA officials here told The Jerusalem Post that since the Basic Law authorizes Abbas to fire his prime minister and form a new cabinet, the PA chairman would not hesitate to take such a move if Hamas does not meet his conditions. "Abbas was elected by a majority of Palestinians that considers the PLO the sole, legitimate representative of the Palestinians," said one official. "Those who voted for Abbas also support the peace process with Israel." "Hamas must change if it wants to form a government," he said. "Otherwise, we will have to take action against them. We won't permit them to destroy all the achievements of the Palestinian Authority." In a bid to avoid a crisis with Hamas, Abbas on Saturday dispatched outgoing Prime Minister Ahmed Qurei to Gaza City for urgent talks with Haniyeh and other Hamas leaders. Following the talks, which were attended by incoming Foreign Minister Mahmoud Zahar, Haniyeh announced that his cabinet would be presented on Monday to the PLC for a vote of confidence and said the new ministers would be sworn in on Wednesday. Haniyeh acknowledged that differences had erupted between him and Abbas, but said they would be resolved only through dialogue and understanding. "There won't be a constitutional crisis," he told reporters. "I have a good relation with Abbas and any disputes will be resolved in a manner that serves the interests of the people." He also denied reports that Abbas had warned him that the new cabinet would have no future unless it agreed to negotiate with Israel. Atef Adwan, a Hamas official who is expected to serve as Minister of State in the new cabinet, warned that Abbas's stance could increase tensions among Palestinians. "It's sad that Abbas is allowing himself to become a tool of pressure on the new cabinet on behalf of Fatah and foreign parties," he said. "His position confirms fears that he is deliberately trying to postpone the inauguration of the cabinet. This will result in internal tensions." Adwan expressed hope that the latest crisis would not lead to a severe power struggle between the various branches of the PA. "The letter places an obstacle on the road to a smooth and quiet transition of powers," he said. Nayef Rajoub, a Hamas legislator who is also expected to serve as a minister in the new cabinet, lashed out at Abbas for threatening to dismiss the Hamas cabinet. "There's no doubt that Abbas was elected and has certain powers, but the Hamas cabinet, which won the confidence of 60 percent of the Palestinians, also has powers and a mandate," he said. "On the basis of this mandate, Hamas will fulfill its pledges to the voters."