Death toll from recent landslides and floods, triggered by monsoon, in Sri Lanka has reached 113, as the island nation has sought international assistance.

The state-run disaster management center, while updating the death toll from an earlier figure of 91, said on Saturday that nearly 100 people were still missing after the worst torrential downpours since 2003 drenched the tropical Indian Ocean island nation.

Sri Lanka's military also issued a statement on Saturday, saying it was doubtful any missing people would be found alive two days after the disastrous monsoon displaced some 27,000 people by the ensuing landslides and flash floods.

"I have my doubts. In landslides, it's difficult to find survivors after two days, and today is the second day," said army Major General Sudantha Ranasinghe.

More than 2,000 military personnel from the army, navy and air force were already undertaking a ceaseless coordinated operation to reach trapped villagers and evacuate those residing in areas likely to be hit by potential mudslides, he added.

Meanwhile, the Sri Lankan Foreign Ministry said in a statement that in coordination with the Disaster Management Ministry, an appeal had been issued to the United Nations and several regional countries in an attempt to receive desperately-needed assistance, particularly "in the areas of search and rescue operations."

India has already sent three of its navy ships, carrying supplies and other aid, the first of which arrived in the capital Colombo on Saturday night.

Landslides, mudslides and raging floods are common during the monsoon season in Sri Lanka. In May last year, over 100 people lost their lives due to a massive landslide in the central regions of the country.