Sri Lanka's former chief justice said on Monday there was "no democracy" in Sri Lanka and Fonseka's detention was against the constitution. Sarath Nanda Silva was speaking a day before Fonseka's court-martial begins.
Former Sri Lankan military chief Gen. Sarath Fonseka
Gen. Fonseka, the 59-year-old former army chief, was arrested last month, soon after being defeated by President Mahinda Rajapaksa in the presidential polls in January.
President Rajapaksa has appointed a three-member tribunal to oversee the trial. Fonseka is accused of engaging in politics while in office and violating military procurement laws. He is also accused of abusing his position as the army chief to seek an arms contract for his son-in law.
Fonseka denies all the charges and says they are politically motivated.
The Sri Lankan civil war ended in May 2009 after a series of military operations against the Tamil Tiger rebels
His supporters, who include the retired chief justice Silva, say the court-martial is aimed at preventing him from participating in parliamentary elections due on April 8. They also believe that the court-martial proceedings are illegal.
In an article published in the Sunday Times newspaper, the retired chief justice said that Fonseka could not be court-martialed because he is, as per the Army Act, neither an army officer nor a soldier.
Fonseka's party has meanwhile confirmed that he will not take part in the court martial proceedings in person. Instead he will be represented by a team of lawyers that will challenge the legality of the trial.
Fonseka has also challenged his arrest in the Supreme Court. The hearing is due on April 26.
President Rajapaksa and Fonseka were allies in the military offensive against the Tamil Tiger rebels last year that ended over 25 years of civil war in the country. But their alliance broke when Fonseka resigned from his post and announced his candidacy for the presidential post. Both leaders claim credit for the victory over the Tamil Tigers.
Editor: Anne Thomas