The National Building Research Organisation (NBRO), which monitors the stability of mountain slopes, said heavy rainfall could further saturate the hills and make them unstable.

"Since rainfall within the past 24 hours has exceeded 150 millimetres, if the rains continue, evacuate to a safe location to avoid the risk of landslides," the NBRO said in a statement.

The latest deluge was brought on by the onset of the monsoon rains, although some of the earlier flooding that began last week has started to subside.

The Disaster Management Centre (DMC) said 607 people had been confirmed dead, with many of those previously unaccounted for now presumed killed in the devastating mudslides.

The number of missing was revised down from 341 to 214, while the number of people affected rose to just over two million.

The number of people in state-run refugee camps fell further to 150,000 from a peak of 225,000 as floodwaters receded in and around the capital Colombo.

Record rainfall triggered the floods and deadly landslides, which President Anura Kumara Dissanayake has described as the most challenging natural disaster in the history of the island.

- Fresh IMF talks -

Addressing parliament on Friday, Dissanayake said he had asked the IMF to delay the release of the sixth instalment of a $2.9 billion bailout loan in order to negotiate a bigger payout.

"The IMF board was to sign off on releasing $347 million on December 15, but we have now asked them to put it off because we want time to negotiate a bigger instalment," Dissanayake said.

He said fresh talks with the Washington-based lender of last resort were essential, because the country's economic situation had drastically changed following the disaster across the island.

Friday's new landslide alert covered areas not previously identified as high risk.

Residents evacuated from the landslide-prone central hills have already been told not to return immediately to their homes, even if they were unaffected by the slips.

In the central town of Gampola, residents worked to clear mud and repair water damage.

"We are getting volunteers from other areas to help with this clean-up," Muslim cleric Faleeldeen Qadiri told AFP at the Gate Jumma Mosque.

"We have calculated that it takes 10 men a whole day to clean one house," said a volunteer, who gave his name as Rinas. "No one can do this without help."

- Broom army -

Sri Lanka's military said it had deployed thousands of troops in flood-hit areas to assist with clearing operations.

The top official in charge of the recovery, Commissioner-General of Essential Services Prabath Chandrakeerthi, said reconstruction costs were estimated at between $6 billion and $7 billion.

Dissanayake announced a raft of measures to offer generous compensation to the victims to rebuild their homes as well as livelihoods.

While the government has sought donations to recover from extensive damage to roads, bridges, homes and industries, tourism authorities said hotels were back in business.

Nearly 300 tourists who were stranded due to the disaster have been rescued by helicopter, the tourism ministry said.

"We need tourism revenues to help rebuild," Deputy Tourism Minister Ruwan Ranasinghe told reporters in Colombo.