The military said a lull in torrential monsoon rains had allowed it to deploy aircraft, boats and ground troops to evacuate people from flooded areas and deliver food and other essentials.
Almost half a million people have had to abandon their homes after the island suffered its worst flooding in 14 years.
The Disaster Management Centre said 169 people had been confirmed dead, most of them buried by landslides triggered by Friday's intense rains. Another 102 people are listed as missing and 88 are in hospital.
Sri Lanka is regularly hit by flooding at the start of the annual monsoon. But carpenter J. H. Siripala, who lives in one of the areas worst hit, said he had never seen it this bad.
Comment: Twelve people are now confirmed killed, and 120 injured, in the wind storm that swept through Moscow on Friday>