Sri Lanka 's sacked prime minister Ranil Wickremesinghe has warned time is running out to avert a "bloodbath" while voicing hope that parliament will resolve a damaging constitutional crisis in the coming days.

Wickremesinghe, who has been holed up at the prime minister's official residence for more than a week as thousands of supporters gather outside, told AFP in an interview that "desperate people" could cause chaos on the Indian Ocean island.

The 69-year-old was sacked out-of-the-blue on October 26 by President Maithripala Sirisena, with domineering former president Mahinda Rajapakse named in his place.

However Wickremesinghe refused to accept his dismissal and has not left the sprawling colonial-era Temple Trees residence -- where Buddhist monks now chant prayers outside -- since.

Sirisena also suspended parliament in an apparent bid to prevent opposition to his move, deepening the turmoil that has seen at least one man killed in a shooting last weekend linked to the power struggle.

"We will be calling on our people not to resort to violence," Wickremesinghe said late Friday. "But you don't know what arises in a situation like this.

"A few desperate people can start off a bloodbath."

His comments echoed the fears of parliament speaker Karu Jayasuriya who warned of bloodshed on the streets if a vote is not held by lawmakers to decide between the two leaders.

Wickremesinghe, head of the United National Party, already the biggest group in parliament, has also called for such a vote and is trying to rally allies to the cause.

But stopping parliament from meeting has given Rajapakse -- still popular despite his strongarm tactics to end the country's Tamil civil war and corruption allegations -- more time to try to win support.

Wickremesinghe said he hoped the showdown could be ended peacefully and expressed optimism that a solution to the crisis would soon be found.

"I feel parliament is going to prevail finally. This can't take too long. I would say in a week to 10 days at the most," he said, adding the priority was to establish parliament's "supremacy".

Wickremesinghe said two smaller parties -- the Marxist Janatha Vimukthi Peramuna and the Tamil National Alliance -- were backing his call for the legislature to meet despite obstacles placed by Sirisena.

The two parties signed a petition to the parliament speaker on Friday demanding the reconvening of the 225-member assembly on November 7.

"A majority of parliament has said all these actions (of the president) are not legitimate and not in accordance with the constitution," said Wickremesinghe.

According to the latest counts, Wickremesinghe has 103 MPs while Rajapakse and Sirisena together have 100. Most of the 22 remaining MPs are expected to back Wickremesinghe, observers said.

Street battles feared 

A majority of legislators want Sirisena to end the suspension of parliament by Wednesday and any delay is "against the wishes of all the parties", according to the embattled Wickremesinghe.

Apart from political pressure on Sirisena, civil society groups are also stepping up agitation to ensure the constitution is respected, Wickremesinghe said.

After sacking his prime minister, Sirisena addressed the nation and lambasted Wickremesinghe, saying they could not work together because of serious personal and cultural differences.

A divorce of their coalition was inevitable after just over three years, Sirisena said. Wickremesinghe had expected a confrontation but not the sack.

"We knew there would be problems by somewhere in November, but it came a bit sooner than I thought," he added.

Sirisena accused Wickremesinghe, a trained lawyer who favours a liberal economy, of being dictatorial and ignoring the president in cabinet.

Wickremesinghe hit back saying their personal rivalry was not an excuse for a constitutional war.

"The constitution doesn't make provisions for personality clashes," he said. "In cabinet there are people you like and you may not like."

Wickremesinghe is from an elitist family with an urban upbringing, poles apart from Sirisena who is from a modest rural farming family.

They made common cause to end Rajapakse's decade in power in a 2015 presidential election but have drifted apart since over economic policy and day-to-day decisions.

Sirisena has also accused Wickremesinghe of being an autocratic leader of the UNP.

"He is not a member of the UNP," Wickremesinghe hit back. "He can say whatever he wants."