Former president Mahinda Rajapaksa, who was appointed as prime minister by President Maithripala Sirisena on October 26, has informed UPFA MPs that he has resigned from PM post, MP Shehan Semasinghe told Daily Mirror.

Rajapaksa signed the resignation letter during a ceremony, reports said.

His son, Namal, told the BBC his father had quit to ensure national stability.

Sri Lanka is passing through a political crisis since late October.

Sri Lanka President Maithripala Sirisena in October sacked Prime Minister Ranil Wickremesinghe and appointed former president Mahinda Rajapaksa as the new premier.

He took oath as the new premier of the country on Oct 26. 

Relations between Sirisena and Wickremesinghe's political parties, who have governed in coalition since 2015, received setback since both suffered humiliating losses in February's local council elections.

Wickremesinghe might return to the office on Sunday.

His party's spokesman Harin Fernando told the BBC: "The president has agreed to swear in Ranil Wickremesinghe as Prime Minister tomorrow at 10 am."