Embattled Mahmoud Abbas got a major boost in his increasingly bellicose showdown with Hamas tonight, with a US diplomat saying he expects a crippling 15-month-old foreign aid embargo to be lifted once the Palestinian president appoints an emergency government without the Islamic militants.

Hamas today challenged the legitimacy of the emergency government that is to be sworn in by Palestinian President Mahmoud Abbas later in the day.

Political rivals Hamas and Fatah will present a national unity government to the Palestinian parliament for approval on Saturday, capping months of stop-and-go negotiations interspersed by periods of deadly factional fighting, officials from both sides said.