Ranil Wickremesinghe on Friday pledged to maintain law and order and revive the 19th Amendment to the Constitution aimed at empowering Parliament over the executive president as he was sworn in as Sri Lanka's interim president until the House elects a successor to Gotabaya Rajapaksa.

Rajapaksa, currently in Singapore, emailed his resignation to Speaker Mahinda Yapa Abeywardena, who said on Friday that he accepted his resignation, which he received late on Thursday.

Rajapaksa's resignation came two days after the embattled leader fled to the Maldives and then flew to Singapore in the face of massive protests against his government for mishandling the economy that bankrupted the country.

Wickremesinghe, 73, was sworn in as the acting president of Sri Lanka before Chief Justice Jayantha Jayasuriya.

Addressing Parliament after he was sworn in as interim President, Wickremesinghe, who is also the prime minister, pledged to strictly maintain law and order in the country which has witnessed massive anti-government protests and occupation of key government buildings.

He said that the armed forces have been given the powers and the freedom to deal with any acts of violence and sabotage.

"I am one hundred per cent supportive of peaceful demonstrations. There is a difference between rioters and protesters," he said.

Wickremesinghe said the true protesters would not resort to unleashing violence.

The parliamentarians who are expected to vote in the process of electing the next President would be given full protection to attend Parliament.

He said as acting President his first task would be to revive the 19th amendment to the Constitution. A draft would soon be prepared for its restoration.

The 19A adopted in 2015 pruned presidential powers by empowering Parliament above the executive president.

Wickremesinghe was the main sponsor of the 19th Amendment in 2015.

However, the 19A was scrapped after Gotabaya Rajapaksa won the November 2019 presidential election.

Wickremesinghe also said a united effort of all parties was needed to tackle the current economic crisis therefore an all-party government should be formed.

Abeywardena told the party leaders that Parliament will meet on July 20 to elect a new president.

He said that nominations will be called for the post of President on July 19. The announcement of the vacancy in the office of President will be officially informed to the Parliament on Saturday.

The Speaker earlier said in terms of the Constitution, Wickremesinghe will function in the capacity of the President overseeing functions, duties, and powers of the office of the President until the constitutional procedure of electing the new President is over.

On Saturday, Rajapaksa announced that he will step down on July 13 after thousands of protesters stormed his official residence, blaming him for the unprecedented economic crisis that has brought the country to its knees.

Under the Sri Lankan Constitution, if both the president and prime minister resign, the Speaker of parliament will serve as acting president for a maximum of 30 days from one of its members, who will hold the office for the remaining two years of the current term.

Prime Minister Wickremesinghe on Wednesday asked the Speaker to nominate a Prime Minister who is acceptable to both the Government and Opposition.

Sri Lanka, a country of 22 million people, is under the grip of an unprecedented economic turmoil, the worst in seven decades, leaving millions struggling to buy food, medicine, fuel and other essentials.