RAMALLAH (Reuters) -Palestinian Prime Minister Mohammad Mustafa formed a new cabinet on Thursday in which he will also serve as foreign minister, making an immediate ceasefire and Israeli withdrawal from Gaza a priority, Palestinian news agency WAFA reported. Mustafa, an ally to President Mahmoud Abbas and a leading business figure, was appointed premier this month with a mandate to help reform the Palestinian Authority (PA), which exercises limited self-rule in the Israeli-occupied West Bank.