RAMALLAH, West Bank - President Mahmoud Abbas on Thursday designated Prime Minister Ismail Haniyeh of Hamas to form a new Palestinian government after accepting his resignation. The move paves the way for installation of a unity government with the Islamic Hamas and Abbas' more moderate Fatah.

Haniyeh has five weeks to form the government along the lines of an agreement hammered out last week at a summit in Mecca, Saudi Arabia.

Last-minute demands by Hamas had raised doubts about whether the Islamic militant group would go ahead with the resignation. However, the disputes were resolved, said Ziad Abu Amr, an independent who is expected to serve as foreign minister in the new Cabinet.

Abu Amr said Hamas and Fatah representatives met in his office and agreed that the Hamas Cabinet led by Prime Minister Ismail Haniyeh of Hamas would resign later Thursday. President Mahmoud Abbas would then hand Haniyeh a letter of appointment as the new prime minister, with a request to form a Hamas-Fatah coalition, Abu Amr said.

Meanwhile, aides to Abbas said the United States has informed him that it will shun any members of a future Hamas-Fatah coalition.

Abbas received word in a phone call from a senior State Department official late Wednesday. A U.S. diplomat then delivered the same message in person Thursday, said the aides, speaking on condition of anonymity because they are not authorized to discuss the issue.

A U.S. spokeswoman in Jerusalem had no immediate comment.