KATHMANDU - Three former Nepali prime ministers joined thousands of demonstrators on Friday to protest against Prime Minister K.P. Sharma Oli's abrupt move to dissolve parliament and call snap elections.

Judges in the Supreme Court are hearing arguments on more than a dozen petitions challenging Oli's plan to seek elections about two years before his government's tenure ends.

Oli, 68, has said internal squabbling and a lack of cooperation from members of his party had paralysed decision-making, forcing his December 2020 move to seek an early vote.

In recent weeks Oli has been attending rallies organised by his supporters in support of his decision that mirror regular demonstrations against it.

On Friday, the protesters demanded that he withdraw his "unconstitutional" move that has plunged the young republic already battling the pandemic into political turmoil.

"We will all continue our protests to pressure Oli to realise his mistake and correct it," former prime minister Madhav Kumar Nepal told the anti-government rally in the heart of Kathmandu.

Former premiers Prachanda, who led a decade long Maoist insurgency that ended in 2006 and still goes by his nom de guerre, and Jhal Nath Khanal, were also at the rally. All three former premiers are from Oli’s party but oppose the dissolution.

A senior police official said an estimated 25,000 people had gathered to protest near Oli's office on Friday and more marches were planned across the Himalayan nation, which lies between India and China.

Legal experts said the hearing on Oli's decision was expected to go on until February as more than 300 lawyers had registered their names to participate in the proceedings.

(Reporting by Gopal Sharma; editing by Philippa Fletcher) ((gopal.sharma@thomsonreuters.com; + 977 1 4372152; Reuters Messaging: gopal.sharma.reuters.com@reuters.net))