More than 40,000 people have been displaced in the north central and east regions of Sri Lanka as torrential rains made dams overflow and hampered transport, an official said on Sunday.
The eastern town of Batticaloa is the worst hit with an estimated 30,000 people displaced from their homes, an official said.
Thousands more had to be evacuated by the army and navy officials, including from tourist hot spots such as Anuradhapura where ancient ruins are a popular attraction.
The towns of Anuradhapura and Polonnaruwa in the north central province are also home to some of Sri Lanka's largest rice cultivation with hundreds of dams scattered around the region to provide water in the usually arid region.
Lashed by heavy showers for days as many as 29 of the big dams and 83 of the medium ones have reached spill level, forcing sluice gates to be opened, threatening people living downriver.
"The safety of pilgrims and foreign visitors is being given priority. They have been evacuated from hotels near major tanks while pilgrims were removed from the sacred city," Anuradhapura District Secretary Mahinda Seneviratne told reporters.
Severe rain is expected to continue during the Christmas week, dampening relief efforts.
Met Department Forecaster Jeewan Karunaratne said a disturbance in the upper atmosphere had activated the northeast monsoon.
"We are expecting heavy rains in the coming weeks as atmospheric disturbances are occurring in a wave pattern," he said. Landslide warnings have also been issued to four districts in central Sri Lanka.
The floods have also hampered road and railway transport services. Saturday's trains carrying mail from Colombo to the east and north were canceled after tracks were submerged at several locations, local media reported.