COLOMBO, Nov. 10 (Xinhua) -- Sri Lanka's ousted Prime Minister Ranil Wickremesinghe's party, the United National Party (UNP), said Saturday it would file a case in the Supreme Court against the early dissolution of parliament by President Maithripala Sirisena.

UNP Parliamentarian Mangala Samaraweera told journalists in a media briefing here that the party would early next week file a challenge in the Supreme Court, calling the president's decision to dissolve parliament "illegal."

A group of UNP legislators on Saturday afternoon met Elections Commission Chairman Mahinda Deshapriya and discussed the dissolution of parliament and urged him to take steps to "save democracy."

Meanwhile the main opposition Tamil National Alliance and the Janatha Vimukthi Peramuna will also be filing cases in the Supreme Court against the dissolution of parliament on Monday, their party spokespersons said.

Sirisena on late Friday signed a special gazette notification dissolving parliament and declaring Jan. 5 as the date for a snap parliamentary election.

The president said the parliament would stand dissolved from Saturday 12 a.m. (local time) and nominations for the parliamentary elections would be called from Nov. 19-26.

Sirisena's move to dissolve the parliament came one and a half years ahead of the scheduled parliamentary polls.

Sri Lanka has been facing a political turmoil since Oct. 26 when the president sacked Prime Minister Wickremesinghe and appointed former president Mahinda Rajapakse to the post.