Hamas will no longer recognise Mahmoud Abbas as Palestinian president after January 8 and will then fill the post with one of its leaders, the Islamic militant movement's legislators, citing Palestinian law, said in a resolution adopted on Monday.

The vote appeared aimed, in part, at stepping up pressure on Abbas, a political moderate, ahead of a new attempt by Egypt to mediate a power-sharing deal between the two rival camps. The resolution left a loophole, suggesting that Abbas' term could be extended by parliament if deemed to be in the "national interest".

However, Monday's vote also marked another step toward deepening the rift between the rivals. Hamas has been in control of Gaza since its violent takeover of the territory in June 2007, leaving Abbas only in charge of the West Bank, and animosity has been growing.

Reconciliation appears increasingly unlikely, since neither side appears to have a compelling interest to share power. Hamas has consolidated control of Gaza and kept the territory afloat despite a virtual blockade of its borders, while Abbas would risk Western support if he agreed to a partnership with the militants. Hamas is considered a terrorist group by Israel, the US and EU.

Abbas, the leader of the moderate Fatah movement, was elected president in January 2005. A year later, Hamas defeated Fatah by a landslide in parliamentary elections. The Basic Law, a forerunner to a Palestinian constitution, says both president and parliament are elected to four-year terms.

Before leaving office, the Fatah parliament passed a law stipulating that future presidential and parliamentary elections be held simultaneously.

However, the subsequent Hamas-controlled parliament never amended the Basic Law to include this new clause. As a result, Hamas argues Abbas' term ends in January, while Fatah argues that he can stay in office an extra year.

If Hamas actually withdraws recognition from Abbas, it would sever another link between the two sides and also undermine Abbas' legitimacy in the eyes of many Palestinians.

The Hamas resolution demands that Abbas issue a decree by Wednesday to hold new presidential elections within three months, to coincide with what Hamas says is the end of his term.

If he does not, Hamas says it will install deputy parliament speaker Ahmed Bahar of Hamas as Abbas' temporary successor until elections are held.

The job would normally go to the parliament speaker, Abdel Aziz Dueik, also of Hamas, but Dueik is in an Israeli jail, along with scores of other Hamas lawmakers from the West Bank. Bahar said Monday he would accept the job, if asked.

In the West Bank, Abbas aide Nimer Hamad said Hamas was trying to exert pressure ahead of the Egyptian-brokered talks, which are expected to begin next month. "I believe Hamas is coming to this point just to undermine the national dialogue before it starts in Cairo," he said.

Hamad added that presidential elections could not be held as long as the Palestinians are divided. "There will be no elections without national reconciliation," he said.