The court martial of Sri Lanka's former army chief resumed on Tuesday, two days before parliamentary elections at which he is a candidate, a military official said.
Sarath Fonseka, who has been in detention since February 8, appeared at the hearing in the tightly-guarded naval headquarters in Colombo.
"General Fonseka is at the hearing which re-opened this morning into allegations that he was involved in politics while in uniform," the official said, without giving further details.
Fonseka will face a second set of charges later Tuesday on alleged corrupt military procurements.
The general denies all charges and says they are part of a political vendetta against him.
Fonseka, 59, who led the military to victory over the Tamil Tiger rebels last year, fell out with President Mahinda Rajapakse and unsuccessfully tried to unseat him in elections in January.
He is a candidate from the opposition Democratic National Alliance at Thursday's parliamentary polls. His party has said that his arrest and detention was aimed at preventing him from campaigning.
Rajapakse, whose party looks set to win Thursday's elections easily, has been accused by political opponents and international human rights groups of suppressing dissent since his resounding re-election.
Fonseka entered politics after quitting the military in November, six months after the separatist Tamil rebels were finally crushed.
Fonseka was arrested 12 days after he lost the presidential election to Rajapakse.