KATHMANDU - Nepal's top court began hearings on Wednesday on petitions challenging Prime Minister K.P. Sharma Oli's sudden decision to dissolve parliament, as protesters against his move marched nearby.

Oli, 68, has cited internal squabbling within his ruling Communist party and lack of political unity as reasons behind his Dec. 20 decision, which has triggered public outrage and has been labelled unconstitutional.

In their plea before the Supreme Court, politicians, activists and lawyers are questioning whether it is the legitimate right of the leader to dissolve the parliament and order fresh elections, 18 months before schedule.

His colleagues and opposition political parties have blamed Oli for derailing a stable government amid a pandemic that has triggered an economic downturn.

Seven ministers have quit Oli's government to oppose his move and protesters last month burnt effigies of him.

On Wednesday, dozens of peaceful protesters carrying lanterns marched near the parliament building. Displaying objects such as lanterns and torches is common in Nepal as a mark of protest.

"Cancel the unconstitutional coup," protesters shouted referring to Oli's move.

The five-member constitutional bench of the Supreme Court, including the chief justice, is hearing at least 13 petitions questioning the rights of the prime minister, court official Bhadrakali Pokharel said.

Dinesh Tripathi, one of the petitioners, said the constitution laid down the limits of the powers of the prime minister.

"It does not give Oli the prerogative to cause an untimely death to parliament at his will," he said.

The court could take several days to give its verdict, legal experts say.

"We are fully prepared to face the challenge in the court," said Rajan Bhattarai, an aide to Oli.

(Editing by Rupam Jain and Sanjeev Miglani; Editing by Kim Coghill) ((gopal.sharma@thomsonreuters.com; + 977 1 4372152; Reuters Messaging: gopal.sharma.reuters.com@reuters.net))