ISLAMABAD - Pakistani opposition parties began mapping out on Tuesday a list of demands that President Pervez Musharraf must meet to prevent their boycott of a January general election.

Former prime ministers Benazir Bhutto and Nawaz Sharif met in Islamabad on Monday and decided to set a deadline for the government to meet their demands, or else they would "move towards" a boycott of the January 8 vote.

A full opposition boycott would rob the vote of credibility and prolong instability in the nuclear-armed country that is crucial to U.S. efforts to fight al Qaeda and bring peace to neighbouring Afghanistan.

Bhutto has previously said her party would reluctantly take part in the vote, while reserving the right to withdraw or to protest against an unfair result.

Sharif has called for a boycott unless judges Musharraf purged when he declared emergency rule on November 3 were reinstated.

Sharif registered to run nonetheless, but his nomination was rejected on Monday because of criminal convictions after his 1999 ouster by Musharraf that Sharif says were politically motivated.

Despite his disqualification, Sharif has not ruled out his party's participation.

Representatives of Bhutto, Sharif and other opposition parties were due to meet on Tuesday to forge a united stand and draw up a "charter of demands" to be implemented before the vote.

"We are already running short of time. We will try our best to finalise the demands, at the latest by tomorrow," said Ahsan Iqbal, a spokesman for Sharif's party.

Old rivals Sharif and Bhutto have both recently been allowed back into the country after years in exile.

Musharraf, bowing to international and domestic pressure, stepped down as army chief last week and was sworn in as a civilian president.

He also promised that emergency rule would be lifted on December 16, fulfilling two main demands of his rivals and the his Western backers, including the United States.

CARETAKER GOVERNMENT

But the opposition say Musharraf must do more.

The opposition has yet to announce their demands or the government's deadline for meeting them, but Iqbal said they had objections over the neutrality of a caretaker government installed last month by Musharraf to oversee the election.

Caretaker prime minister Mohammadmian Soomro and many members of his cabinet belong to Pakistan Muslim League (Quaid-e-Azam), a grouping that was cobbled together from the remnants of Sharif's party as a political powerbase for Musharraf after his 1999 coup.

Bhutto said one of her main demands was an independent Election Commission to prevent vote rigging.

However, the main sticking point between Bhutto and Sharif is the question of the judges Musharraf dismissed after the imposition of emergency rule.

Sharif and some smaller parties want the judges reinstated while Bhutto's Pakistan People's Party says the matter should be left to a new parliament.

"We will see how to accommodate the People's Party position," Iqbal said.

Musharraf has ruled out letting the judges back, some of whom remain under house arrest.

Analysts expect both of the main opposition parties will eventually take part after extracting maximum concessions.

Sharif was sent into exile in 2000 after being convicted on hijacking and corruption.

Bhutto also faced corruption charges, but the government dropped them in the hope that liberal-minded politician would cut a power-sharing deal with Musharraf.

Prospects for a post-election deal dimmed after Musharraf invoked emergency powers.