"It is expedient, so to do, in the interests of public security, the protection of public order and the maintenance of supplies and services essential to the life of the community," Ranil Wickremesinghe said in a statement.

Sri Lanka's former president Gotabaya Rajapaksa fled the country last week after nationwide mass protests calling for his resignation.

Wickremesinghe was sworn in as acting president on Friday. He is also the country's prime minister.

A new head of state is due to be picked on Wednesday, and Wickremesinghe is one of two frontrunners to take on the presidential role permanently, according to Deutsche press agency (dpa). There are four candidates.

Some protesters are calling for Wickremesinghe to resign as well seeing him as an ally of Rajapaksa.

Sri Lanka, an island state of some 22 million people, is currently in its most severe economic crisis for decades, with drastic fuel shortages.

Protests have largely subsided since Rajapaksa fled the country and resigned, but some 500 people continue to occupy parts of the presidential palace after it was stormed by demonstrators at the height of the civil unrest.