There are fears of violence between rival military units if talks remain stalled [Reuters]

Talks aimed at ending the political standoff in Yemen between Ali Abdullah Saleh, Yemen's president, and the opposition have stalled, according to opposition officials.

But in a sign that there was not a complete stalemate, the ruling party's governing committee on Sunday recommended forming a new government to draft a new constitution on the basis of a parliamentary system.

"Members of the central committee of the People's Congress stress the quick need to form a government tasked with drafting a new constitution for the country on the basis of a parliamentary system," the website of the defence ministry said.

Saleh, who has been in power for 32 years, is under pressure from tens of thousands of Yemenis who have taken to the streets demanding he step down.

The president has alternately been defiant and conciliatory towards the protesters.

He has offered some concessions, such as pledging not to seek another period in office beyond 2013, but demonstrators and anti-government activists want him to step down much sooner.

They are also unwilling to offer guarantees that Saleh and his family will not face prosecution after he leaves office.

Al Jazeera's special correspondent in Sanaa said that the negotiations appeared to have stalled following an interview that Saleh gave to Al Arabiya television in which he made clear that he would not step down until elections took place at the end of the year.

"This kind of stalemate - and we've heard that talks did not take place at all today [Sunday] and they are unlikely to take place on Monday - is very worrying for the general public," she said.

"People fear that violence may fill the vacuum that is left by the deadlock in these negotiations."

Talks suspended

On Sunday, an aide to General Ali Mohsen, a key military leader who has sided with the protesters, said of the talks: "Yesterday evening they stopped."

Asked if he anticipated talks would resume, he said: "Until now, absolutely not."

A spokesman for Yemen's main opposition coalition also said the talks had been halted, a development that if it continues would likely raise fears that violence between rival military units could replace the political process.

There was no immediate comment from the government.

Away from the political drama in Sanaa, the Yemeni capital, troops clashed with fighters in the south of the country.

The army on Sunday tried to dislodge an armed Islamist group that had taken control of several key buildings, including an ammunition factory, in the town of Jaar in Abyan province.

One soldier was reported killed in the clash and other reports suggested that the police had deserted the town. A day earlier, five soldiers were killed in an ambush in Lowdar, also in Abyan.

The province is seen as a stronghold of al-Qaeda in the Arabian Peninsula, the Yemeni wing of the network which Western countries and neighbour Saudi Arabia fear could take advantage of any power vacuum if protesters succeed in ousting Saleh.

'Time bomb'

Robert Gates, the US defence secretary, said on Sunday that the replacement of Saleh by a weaker leader would pose "a real problem" for the US.

"I think it is a real concern because the most active and at this point perhaps the most aggressive branch of al-Qaeda, al-Qaeda in the Arabian Peninsula, operates out of Yemen," Gates said.

"And we've had counter-terrorism co-operation with President Saleh and the Yemeni security services.

"So if that government collapses, or is replaced by one who is dramatically more weak, then I think we'd face some additional challenges out of Yemen, there's no question about it. It's a real problem."

Both Washington and Saudi Arabia have backed Saleh in a bid to keep al-Qaeda from expanding its foothold in a country many political analysts say is close to collapse.

In his interview to Al Arabiya, Saleh warned that Yemen would slide into civil conflict if he left immediately.

"Yemen is a time bomb and if we and our friendly countries don't have a return to dialogue, there will be a destructive civil war," he said.

More than 80 people have been killed since anti-government protests started in January.