Sri Lankan President Mahinda Rajapaksa has ruled out an early pardon for his defeated presidential rival and former army chief General Sarath Fonseka.

According to the BBC, President Rajapaksa described Gen Fonseka as a "fool" who had himself put thousands of soldiers on trial.

Gen Fonseka is on trial by the army. He is charged with taking part in politics while in uniform and breaking procedure on military procurement.

Gen Fonseka says the charges are politically motivated.

The president said the law must apply to everyone and the process of trying the retired general must not be interrupted.

This week the UK-based Channel 4 News said that Gen Fonseka, in a letter smuggled from detention, had appealed to Sri Lankans to help obtain his release from "the clutches of tyranny, corruption and nepotism".

The general says the charges are levelled by the government to malign him ahead of next month's general election.

Gen Fonseka is standing despite being detained.

He was arrested by the army last month after losing presidential elections to Mr Rajapaksa in January. (ANI)