Sri Lankan authorities on Monday imposed a nationwide curfew and Army troops were deployed in the capital after pro-government groups attacked protesters outside embattled President Gotabaya Rajapaksa's office, leaving at least 23 people injured.

Sri Lankan Prime Minister Mahinda Rajapaksa resigns.

The violence occurred following reports that Mahinda Rajapaksa may offer to stand down as Prime Minister, as pressure mounted on the embattled government led by his younger brother and President Gotabaya Rajapaksa to form an interim administration to overcome the worst economic crisis facing the country.

Curfew was imposed islandwide with immediate effect until further notice, a police spokesperson was quoted as saying by the local media. A military contingent was deployed to the protest site to assist law enforcement.

At least 23 people were injured as supporters of Prime Minister Mahinda Rajapaksa on Monday attacked anti-government demonstrators gathered at a protest site near his official residence to demand for the premier's resignation.

The violence occurred following reports on Monday that Mahinda Rajapksa may offer to stand down as Prime Minister, as pressure mounts on the embattled government led by his younger brother and President Gotabaya Rajapaksa to form an interim administration to overcome the worst economic crisis facing the country.

Rajapaksa, 76, under intense pressure from within his own Sri Lanka Podujana Peramuna (SLPP) ranks to resign, was gathering his supporters to apply counterpressure not to stand down.

"While emotions are running high in #lka, I urge our general public to exercise restraint & remember that violence only begets violence.

The economic crisis we're in needs an economic solution which this administration is committed to resolving," Prime Minister Mahinda tweeted.

'Nothing would deter me'

Earlier, Rajapaksa told his thousands of supporters gathered outside his house that nothing would deter him. "I am so used to seeing protests and agitations, nothing would deter me. I am experienced enough to face any situation," Rajapaksa said.

A tense situation prevailed as a group of supporters of Prime Minister Mahinda Rajapaksa attacked the protesters outside the 'MainaGoGama', a protest site near Temple Trees, the official residence of the Prime Minister, Daily Mirror, an online news platform, reported.

The tents opposite Temple Trees were dismantled by a mob, Lanka First, a leading news network, reported.

Police use water cannons

Police used water cannons to disperse the unruly SLPP protestors who are at the Galle Face green protest site, Hiru News website reported.

At least 23 people were injured in the violence.

The police formed a human chain to prevent the protesters from entering GotaGoGama.

However, the mob pushed their way past the police human chain and attacked GotaGoGama.

A military contingent was deployed to the protest site to assist law enforcement.

Opposition leader visits site

Opposition leader of the Samagi Jana Balavegaya Sajith Premadasa visited the GotaGoGama protest site to assess the situation.

The Opposition sources said a group had also attacked Premadasa and his colleagues as he arrived at the presidential secretariat protest site.

It accused Mahinda Rajapaksa of instigating his supporters. Later, the government deployed Army troops to bring the situation under control.

The Rajapaksa brothers - President Gotabaya Rajapaksa and Prime Minister Mahinda Rajapaksa - have so far defied calls for their resignation.

State of emergency

In a special Cabinet meeting on Friday, President Gotabaya Rajapaksa declared a state of emergency with effect from Friday midnight. This is the second time that an emergency was declared in Sri Lanka in just over a month as the island nation was in the grip of the worst economic crisis.

Sri Lanka is currently in the throes of unprecedented economic turmoil since its independence from Britain in 1948.

The crisis is caused in part by a lack of foreign currency, which has meant that the country cannot afford to pay for imports of staple foods and fuel, leading to acute shortages and very high prices.

Thousands of demonstrators have hit the streets across Sri Lanka since April 9, as the government ran out of money for vital imports; prices of essential commodities have skyrocketed and there are acute shortages in fuel, medicines and electricity supply.