Flash floods have killed at least 25 people in Sri Lanka and left more than a quarter of a million marooned in their homes, disaster officials said Thursday.

Heavy rains, which have battered the island for much of the week, were still being reported in 14 of Sri Lanka's 25 administrative districts, with the central highlands -- one of the world's key tea producing regions -- the worst hit.

Sarath Lal Kumara, the deputy director of the Disaster Management Centre, said that 25 people were now known to have died and a further 36 remained missing.

Most of the deaths were due to landslides engulfing homes.

The disaster management centre said more than 265,000 people had been cut off in their homes by the floods and thousands more had either sought refuge with relatives and friends or else been given emergency shelter.

"We have housed some 18,845 people from over 5,000 families in 102 relief camps", Kumara told AFP.

Many of the evacuations took place in the central district of Matale after authorities declared it a danger zone over landslide fears.

Bhadra Kamaladasa, the director general of irrigation, said that around half of the country's 71 main reservoirs were overflowing.

In the west coastal town of Chilaw at least five fishermen had gone missing. The main motorway and the town were under six feet of flood water, police said.

The Railway Department announced the disruption of several key services as the tracks remained submerged.

The floods are some of the worst in Sri Lanka since early 2011 when unusually heavy monsoon rains left at least 64 people dead and drove more than one million people out of their homes.