The widower of Benazir Bhutto held talks with leaders of his Pakistan People's Party on Monday to decide on a candidate for prime minister after agreeing on a coalition that could force President Pervez Musharraf from power.

Asif Ali Zardari, who became head of the PPP after Bhutto's assassination in December, signed an agreement on Sunday with former prime minister Nawaz Sharif to form a coalition government.

The pact sets the scene for confrontation with US ally Musharraf, particularly as Zardari and Sharif promised to reinstate judges Musharraf dismissed in November, just as they were expected to rule his October re-election by legislators, while still army chief, unconstitutional.

The two leaders also agreed that the PPP should nominate a candidate for prime minister as it won the most seats in  February 18 elections, though not enough to rule alone. Sharif's party came second while the main pro-Musharraf party came a poor third.

Zardari had begun sounding out members-elect of his party before deciding on a candidate, a party spokeswoman said.

"The members have reposed full confidence and given full authority to Mr Zardari to name the candidate for the prime minister," Sherry Rehman, a spokeswoman for the party, told reporters after Zardari met his party members-elect.

Musharraf said last week it would be a week or more before the National Assembly was convened but Sharif and Zardari said on Sunday the session should be called immediately.

Makhdoom Amin Fahim, Zardari's deputy and a close aide to Bhutto, had been seen as the likely choice for prime minister but his absence from Sunday's talks between Zardari and Sharif has fuelled speculation he might be out of the running.

Ahmed Mukhtar, an industrialist and commerce minister in Bhutto's cabinet, has emerged as another strong contender.

Zardari can't become prime minister because he did not contest the elections and a prime minister must be a member of parliament. But some party members want him to stand in a by-election and go for the top job.

"We told him that it's been a tradition that the chairperson of the party should also be prime minister," said a PPP member elected to the National Assembly who met Zardari at the weekend. "We told him we will fully support him if he becomes prime minister," said the politician, who declined to be identified.

Western allies and Pakistan's neighbours, concerned about instability in a nuclear-armed state reeling from militant suicide bombings, fear more political upheaval in case of confrontation between the president and the new government. - Reuters