Sri Lanka's main party of Buddhist monks has announced it is leaving President Mahinda Rajapaksa's government in protest over what they say is his refusal to curb powers and carry out demands for democratic reforms before fresh elections.

JHU, or National Heritage Party, announced the move on Tuesday - Rajapaksa's 69th birthday - in advance of presidential elections expected to take place in January , two years ahead of schedule.

"This [quitting] is not a challenge from an enemy force," Omalpe Sobitha, JHU leader, said.

"This is a birthday gift to the president to correct his ways. This is the advice of a friend given according to the teachings of the Buddha."

Sobitha said Rajapaksa had failed to ensure the independence of the judiciary and restore rule of law and end corruption since the military crushed the rebels.

"I have today given my letter of resignation to the president," Champika Ranawaka, a JHU legislator and Sri Lanka's technology minister, said.

"Our other elected members too have given up their responsibilities. We will no longer be subject to the whip of the UPFA (United People's Freedom Alliance) government."

JHU has just three seats in the 225-member parliament, but the monks are considered influential among the country's majority Buddhist community.

The party supported Rajapaksa's election in 2005 and backed his moves to end a decades-long separatist war by crushing Tamil Tiger rebels in 2009.

JHU had hoped he would reform the constitution after winning re-election in 2010.

JHU threatened action against Rajapaksa earlier this month unless he moved on reforms.

Government ministers have said Rajapaksa will seek election for a third term in January, attempting to secure another mandate before his party's popularity falls further.

Rajapaksa came to power in 2005 promising to revert to a Westminster-style parliamentary democracy. But he secured a second term in 2010 and rewrote the constitution, removing the two-term limit on the top job and giving himself more powers over the administration.

Rajapaksa's UPFA vote share fell at local elections in September, suffering its worst performance since he first came to power nine years ago.

Source: Agencies