The United States on Sunday urged Sri Lankan leaders to act quickly to seek long-term solutions after the president was chased from his residence and announced his resignation.

As President Gotabaya Rajapaksa prepares to step down, the United States calls on "the Sri Lankan parliament to approach this juncture with a commitment to the betterment of the nation -- not any one political party," a State Department spokesperson said as Secretary of State Antony Blinken visited Thailand, reports AFP.

"We urge this government or any new, constitutionally selected government to work quickly to identify and implement solutions that will achieve long-term economic stability and address the Sri Lankan people's discontent over the worsening economic conditions, including power, food and fuel shortages."

The United States warned against attacks on protesters or journalists, but also criticised violence on Saturday as a mob stormed Rajapaksa's residence.

"The Sri Lankan people have the right to peacefully raise their voices, and we call for the full investigation, arrest and prosecution of anyone involved in any protest-related violent incidents," the spokesperson said.

Rajapaksa has had a rocky relationship with the United States over his dismissal of allegations of war crimes in the bloody finale of Sri Lanka's decades-long civil war and his close economic partnership with China.

Both the United States and China have offered in recent weeks to support the once-prosperous island as it grapples with unprecedented fuel and food shortages.