Chief Justice Jayantha Jayasuriya administered his oath to office.

He was sworn in after the resignation of President Gotabaya Rajapaksa, Daily Star reported.

In a televised speech soon after he was formally sworn in as the Acting President, Wickremesinghe also said that he had done away with the President's flag and the long-standing custom of addressing the Head of State as "His Excellency". Sri Lanka only needs the national flag, he said.

He made it clear that he had nothing against the anti-government struggle or Aragalaya as it is known whose supporters on July 9 overran the President's House, forcing President Gotabaya Rajapaksa to eventually flee Sri Lanka, and also the Presidential Secretariat and the Prime Minister's official residence, Temple Trees.

"I am not against the peaceful Aragalaya (struggle). However, one needs to identify the difference between the insurgents and protesters," he said in his brief speech.

"It is the insurgents who have taken away the weapons of two policemen and have injured 24 army personnel. These insurgents are trying to create unrest next week. We cannot allow it. Unrest will lead to economic turmoil as distribution of essential items such as food, fuel and gas will come to a standstill.

"Therefore, I have appointed a committee comprising service commanders and IGP (Inspector General of Police). They are in charge of maintaining law and order."

Wickremesinghe did not name the "insurgents" but he was clearly referring to protesters who have been increasingly violent in recent days, snatching away two T-56 assault rifles from security forces, of invading the state-run television and of burning down Wickremesinghe's private residence in Colombo.

He also said all steps will be taken to allow MPs to exercise their free will to elect a new President on July 20.

"There are certain groups who are out to inflict undue influence on MPs on July 20 when they vote to elect a new President. Therefore, all steps will be taken to ensure their security."

The veteran politician, who was named the Prime Minister following the resignation on May 9 of Mahinda Rajapaksa amid widespread violence, pledged to take quick steps to fully implement the 19th amendment of the Constitution again.

"The new President will only have to implement these reforms."

"I also invite all parties to come to an agreement to form an all-party government. It's time to forget political aspirations of individuals. There should be a country for us to engage in politics. Therefore, I invite all political parties to be a part of the process of rebuilding the nation," he said.

Sri Lanka is confronting widespread shortages of even essential commodities like fuel, food and medicines in the wake of its worst economic crisis that has left the country without any foreign exchange to import what the people need.