Sri Lanka's "ousted" Prime Minister Ranil Wickremesinghe on Monday reiterated his call for parliament to be summoned immediately in order to resolve the ongoing political crisis.

Speaking to the Foreign Correspondents Association from his official residence in capital Colombo, Wickremesinghe maintained that he was still the island country's prime minister despite that President Maithripala Sirisena sacked him days earlier.

He said he still enjoyed a majority in parliament and would prove his numbers when sittings convene.

"I am confident I am the only person who can get a majority in parliament. If anyone else feels they have a majority, they can prove it in parliament as the parliament is the supreme authority," he said.

Wickremesinghe further said that several political parties including his United National Party and the opposition Tamil National Alliance had written to the Speaker and expressed concerns over the present political environment and called for parliament to be summoned.

A government minister told Xinhua that 126 political legislators out of the 225-member parliament had signed a letter asking for parliament to be summoned and handed it over to Speaker Karu Jayasuriya.

President Maithripala Sirisena last Friday in a shocking move sacked Wickremesinghe and appointed former President Mahinda Rajapaksa to the post.

Sirisena said Wickremesinghe had lost a majority in parliament after his United People's Freedom Alliance quit the nation's national unity government.

Rajapaksa assumed office as new prime minister earlier on Monday, vowing to strengthen economy and work for the betterment of the nation.

Local media reports said a new caretaker government is expected to be sworn in later on Monday.