Pakistan's opposition election winners were trying to forge a coalition, raising the prospect of a government intent on forcing US ally President Pervez Musharraf from power.

Leaders of the two parties that won the election, the Pakistan People's Party (PPP) and the Pakistan Muslim League (Nawaz), vowed on Thursday to work together to form a government but said they still had details to work out.

The main party backing the unpopular Musharraf was dealt a stunning defeat in Monday's general election, leaving the president, one of Washington's top Muslim allies against Al Qaeda, vulnerable to a hostile parliament.

"I don't see any problems in them forming a coalition," said political analyst and academic Rasul Baksh Rais. "They have realised that by working together they can put Pakistan back on a democratic line."

Nawaz Sharif, the prime minister Musharraf overthrew in 1999 and whose PML-N came second in the vote, has demanded the unpopular president step down. But since the election, Musharraf has said he was not ready to resign.

US President George W. Bush's administration has urged the next government to work with Musharraf and says Washington needs Pakistan - which borders Afghanistan where US and Nato forces are fighting Islamist militants - as an ally.

Sharif met Asif Ali Zardari, former Prime Minister Benazir Bhutto's widower and leader of her PPP since her murder on December 27, in Islamabad on Thursday evening for their first face-to-face talks since the election.

If they forge a coalition, it will be the first time in Pakistan's history the two main parties have come together. Musharraf's 1999 coup ended a chaotic decade of civilian rule alternating between Bhutto and Sharif governments.

Zardari met the PPP's winning candidates, and a party statement said more consultative meetings were expected over the next three days. Zardari and Sharif also separately met with leaders of the Awami National Party, a Pashtun nationalist party set to join them in a coalition after sweeping Islamists out of power in North West Frontier Province.

The Election Commission is expected to issue official results on March 1.    Musharraf should then convene an inaugural session of the National Assembly. But how soon after may depend on whether there is a government-in-waiting, as the president has to invite a member commanding the confidence of the majority to become prime minister.

Sharif told a news conference after his meeting with Zardari that the two parties would work together to form a government. Zardari, whose party won the most seats but not an overall majority, said he wanted a broad government but one excluding the main party that backs Musharraf.-Reuters