Sri Lanka's entire Cabinet will resign once an agreement is reached to form an all-party government, the prime minister's office said on Monday.

It comes as authorities try to overcome a political crisis triggered by an economic collapse.

“All the ministers who participated in the discussion were of the opinion that as soon as there is an agreement to form an all-party government, they are ready to hand over their responsibilities to that government,” said the office of Prime Minister Ranil Wickremesinghe, who has already offered to quit.

Sri Lankan President Gotabaya Rajapaksa had informed Mr Wickremesinghe that he will resign, the prime minister's office said earlier on Monday.

It follows tens of thousands of protesters storming the official residences of both men over Sri Lanka's economic crisis.

The capital Colombo was calm on Monday as hundreds of people strolled into the president's offices and residence, touring the colonial-era buildings. Police made no attempt to stop them.

“We are not going anywhere till this president leaves and we have a government that is acceptable to the people,” Jude Hansana, 31, told Reuters.

“The people's struggle is for wider political reforms. Not just for the president to leave. This is just the start.”

Sri Lanka’s opposition parties met on Sunday to agree on a new government.

Soldiers were stationed around the city, but troops looked on as crowds of people splashed in the pool of Mr Rajapaksa’s sprawling residence, lounged on beds and took selfies.

The chief of defence staff, Gen Shavendra Silva, called for public support to maintain law and order.

Occupants of the prime minister’s official residence cooked in an outdoor kitchen, played the tabletop game carom and slept on sofas.

Ranjith Madduma Bandara, a senior official in the main opposition United People’s Force, said that separate discussions had been held with other parties and legislators who broke away from Mr Rajapaksa’s ruling coalition. More meetings were planned.

Mr Wickremesinghe said on Saturday he would leave office once a new government is in place. Hours later, Speaker of Parliament Mahinda Yapa Abeywardena said Mr Rajapaksa would step down on Wednesday.

Pressure on Mr Rajapaksa and Mr Wickremesinghe had grown as the economic meltdown led to acute shortages of essential items, leaving people struggling to obtain food, fuel and other necessities.

If both president and prime minister resign, the Speaker will take over as temporary president, according to the constitution.