The decision set the stage for a showdown with the Islamists who have been in power for less than a year.

Abbas's media advisor, Nabil Amr, is due Sunday to outline steps the president planned to take after saying early elections were the only way out of a spiralling political crisis.

Abbas told the executive committee of the Palestine Liberation Organisation (PLO) Saturday that he had no alternative but to call an early vote after months-long unity government talks with the Islamist Hamas collapsed.

"There is no choice for me except turning to early elections," a senior Palestinian official quoted Abbas as telling the meeting.

Abbas is due to announce his decision formally in a speech Thursday, when he will make the case for taking this step while still keeping the door open to Hamas for talks, the official said.

"In my speech I will inform the people of my decision, but I will also tell them that the door of dialogue is not closed," Abbas was quoted as saying.

Hamas, which won a stunning upset in a parliamentary vote in January, called the decision an attempt to overthrow the democratically elected Palestinian government and vowed to fight the move.

Palestinian prime minister and Hamas leader Ismail Haniya, in Tehran during his first official trip abroad, blasted Abbas's plan, saying it would accentuate "the crisis and tensions.

"I think that the invitation to carry out the elections in this way is disrespectful to the Palestinian people," Haniya told Iranian television after Abbas's announcement.

"I believe that this will increase the tension and have a negative impact," he added.

In Gaza, the chief of Hamas lawmakers in parliament told AFP the move "is a clear coup against democracy. The goal of this decision is to kick Hamas out of the Palestinian political scene."

Khalil al-Hiyya said Hamas was studying its options.

"If the president calls new elections there will be a response from Hamas," Hiyya added. "How can Hamas agree to hold elections twice in less than one year?"