Over 260,000 people were marooned by flash floods in Sri Lanka's Western Province, relief officials said Thursday.

"We have housed over 200,000 people in 16 relief camps in the Colombo district while over 35,000 in the Kalutara district and over 8,000 in the Gampaha district are also distressed," Pradeep Kodippily, Assistant Director of National Disaster Management Center said.

Some 440 millimeters of rain lashed the capital Colombo by Thursday morning, leaving most parts of the city under floods.

"The rains were caused by the winds of northern and southern hemisphere converging at the inter-tropical convergence zone. 440 mm of rain was the highest since the 493.2 mm recorded on June 4, 1992", Chaminda de Silva, a meteorological official said.

The traffic came to a standstill with long queues of vehicles trying to enter Colombo as most suburbs went under water with the worst rain fall for 18 years.

Power supplies in some areas were switched off as a precaution as grid stations went under water.

All three military forces were deployed to assist flood victims with the navy deploying nine boat squads to ferry people. Helicopters and some 2,000 soldiers were also deployed to assist the victims, a military spokesman said.