Sri Lankan President Gotabaya Rajapaksa has confirmed he will resign, the prime minister's office has said, after tens of thousands of protesters stormed the official residences of both men.

Sri Lanka is in deep financial crisis and the crowds say they won't leave until both men quit their posts.

The parliament Speaker had earlier said the president would resign on 13 July.

Mr Rajapaksa, whose whereabouts are unknown, has not spoken publicly since his residence was stormed on Saturday.

Sources have told the BBC he is on a navy vessel in Sri Lankan waters. He was moved to safety before protesters entered the presidential palace.

The president has been blamed for the country's economic mismanagement, which has caused dire shortages of food, fuel and medicine for months.

The Parliament Speaker first announced his resignation on Saturday, but many Sri Lankans responded with scepticism to the idea that he would relinquish power.

On Monday, Prime Minister Ranil Wickremesinghe's office said in a statement it had been informed by Mr Rajapaksa that he would step down on Wednesday.

But under Sri Lanka's constitution, his resignation can only formally be accepted when he resigns by letter to the Speaker - which has yet to happen.

Prime Minister Wickremesinghe had earlier said he would step down from his position. His house was set on fire during Saturday's unrest.

Inside the occupied palace on Sunday, protesters were refusing to budge.

"Our struggle is not over," student protest leader Lahiru Weerasekara said, quoted by AFP. "We won't give up this struggle until [President Rajapaksa] actually leaves," he said.

"The next couple of days are going to be extremely uncertain times as to see what transpires politically," political analyst and human rights lawyer Bhavani Fonseka told Reuters, adding that it would be interesting to see if the two leaders "actually resign".

Other politicians in Sri Lanka met on Sunday to discuss how to handle a smooth transition of power.

The speaker of Sri Lanka's parliament told the BBC World Service Newshour programme a new cross-party coalition government would need to be formed within a week of the president officially stepping down.

The palace storming on Saturday was the culmination of months of mainly peaceful protests in Sri Lanka.

Huge crowds converged on the official residence of President Rajapaksa, chanting slogans and waving the national flag before breaking through the barricades and entering the property.

Footage online showed people roaming through the house and swimming in the president's pool, while others emptied out a chest of drawers, picked through the president's belongings and used his luxurious bathroom.

Mr Rajapaksa vacated his official residence on Friday as a safety precaution ahead of the planned protests, two defence ministry sources said, according to Reuters.

Although it is Mr Rajapaksa's official residence, he usually sleeps at a separate house nearby. His brother, former Prime Minister Mahinda Rajapaksa, is at a naval base in the country, the sources say.