The trial, which charges Gen Fonseka of participating in politics while in uniform, was due to resume on Tuesday, but it was adjourned because of an outstanding case lodged with Sri Lanka's Court of Appeal challenging the legality of the courts martial.
Another court martial charging the general of breaking army procurement rules is also set to resume on Tuesday, but this may also be adjourned on the same grounds.
General Fonseka says all the charges are politically motivated and an attempt to bar him from forthcoming elections.
He was arrested by the army last month, after losing presidential elections to incumbent Mahinda Rajapaksa in January.
General Fonseka led Sri Lanka's army when it defeated Tamil Tiger rebels last year but he and President Rajapaksa later fell out over who should take credit for winning the war.
Sri Lanka's parliamentary are set to take place on Thursday. (ANI)