"The executive force and Hamas militias are declared outside the law for having carried out an armed rebellion against Palestinian legitimacy and its institutions," Abbas ordered in a decree released by his office.

"Anyone whose ties with these groups are proven will be punished in accordance with the law under the state of emergency," it said.

Abbas sacked the Hamas-led government and declared a state of emergency in Gaza and the West Bank late on Thursday, after Hamas fighters routed forces under his command in the impoverished Gaza Strip.

In Gaza, a spokesman for the Hamas-run executive force brushed aside the decree.

"We reject this decision," said Islam Shahwan. "It reflects the precipitate manner in which Palestinian officials in Ramallah are acting."

Meanwhile, Israeli army units took up positions in northern Gaza on Sunday after it was overrun by the Islamist movement Hamas, Deputy Defence Minister Ephrain Sneh told public radio.

"These are activities of a preventive character, for the moment we are not going on the offensive in the Gaza Strip," he said.

The troops were positioned in the north of the territory near its border with Israel, on the sites of two former Jewish settlements that were dismantled in 2005, he said.

"There are sectors where it's better that it is us who is present rather than others," he said, referring to Hamas, whose charter calls for the destruction of the Jewish state.