There was a "fascist threat" to democracy in Sri Lanka and "we can't let them tear up our Constitution," acting President Ranil Wickremesinghe told the crisis-hit nation on Wednesday, as he vowed to restore normalcy as well as stop the destruction of state property.

In his first televised address since being appointed to the post after embattled President Gotabaya Rajapaksa fled to the Maldives and hours after anti-government protesters stormed the Prime Minister's Office, Wickremesinghe said he had ordered military commanders and the police chief to do what is necessary to restore order.

"We must end this fascist threat to democracy. We can't allow the destruction of state property. The President's Office, the President's Secretariat and the Prime Minister's official residence must be returned to proper custody," he said.

Those who are in my office want to stop me from discharging my responsibilities as acting president. We can't let them tear up our Constitution. We can't allow fascists to take over. Some mainstream politicians too seem to be supporting these extremists. That is why I declared a nation-wide emergency and a curfew, Wickremesinghe said.

Wickremesinghe said he has ordered military commanders and the police chief to do what is necessary to restore order.

He said a committee comprising the heads of armed forces have been given the responsibility to do so with zero political intervention, newsfirst.lk reported.

Wickremesinghe said as Acting President he is declaring a state of emergency and a curfew in the Western province after his office was stormed by protesters.

He said according to intelligence inputs, protesters were to capture his office and Parliament which prompted the action to impose emergency.

Despite the president leaving, and measures taken to elect a new president, some groups in the struggle have organised to take over the Prime Minister's Office, and surround the Air Force Commander's residence for providing an Air Force plane for the President to fly to the Maldives. They had also decided to surround the Navy Commander's residence and Army Commander's residence. These groups tried to obtain control of the country.

"At the same time, they had planned to surround the Parliament...The groups are now protesting around the Prime Minister's Office. There is no reason for them to come here. They want to stop me from being Acting President and stop me from working with the Speaker to elect a new President. They want to appoint their own candidate, Wickremesinghe said.

He said the Constitution will be followed in making all decisions.

Protesters have been demanding resignation of both Rajapaksa and Wickremesinghe to restore normalcy in the country. Wickremesinghe has also pledged that he would step down as prime minister when an all-party government is formed.

Embattled President Rajapaksa fled to the Maldives on a military jet in the morning, hours before he was supposed to quit in the face of a public revolt against his government for mishandling the economy that has bankrupted the country.

From the Maldives, 73-year-old Rajapaksa appointed Prime Minister Wickremesinghe as the acting President, citing Article 37(1) of the Constitution that allows a premier to "discharge the powers, duties and functions of the office of president" when the president is ill or "absent" from the country.

Parliament Speaker Mahinda Yapa Abeywardena announced that Rajapaksa has appointed Wickremesinghe to act to perform his functions while he is abroad.

Abeywardena also said Rajapaksa has informed him over telephone that he will resign today as promised. He said the vote for the new president will take place on July 20.

Meanwhile, the protesters who had arrived in large numbers at the PM Office have surrounded the building. The police fired tear gas on protesters who broke through a barricade and stormed the prime minister's office, calling for his resignation.

Sri Lanka's state-owned television channel Rupavahini briefly suspended its telecast on Wednesday as protesters stormed the building. Later, the channel resumed its transmission.

Also, a second Sri Lankan state television channel went off air, less than an hour after Rupavahini suspended its operations.