|Fonseka unsuccessfully tried to oust Mahinda Rajapaksa, the president, in 2010 presidential polls [Reuters]
Sarath Fonseka, Sri Lanka's jailed former army chief, has lost an appeal to retain his parliamentary seat.
The country's supreme court ruled on Tuesday that a court martial verdict in September that found him guilty of arms procurement offences meant that he was no longer qualified to be a member of parliament.
Prerna Suri, Al Jazeera's correspondent in Colombo, said it ruled that the military tribunal is a fair and constitutional body, giving it authority to try Fonseka on further charges.
"It means all the cases and convictions against him are being upheld," she said.
"His seat in parliament will not be given back to him because under Sri Lanka's constitution those who are serving any kind of prison term are not allowed to contest in parliament, which means he cannot contest in any future elections.
"While Fonseka's legal team plan to challenge the verdict it will take at least 3-6 months, so for now at least Fonseka's political career is almost over."
Fonseka led the army to victory over the separatist Tamil Tiger fighters in May 2009, ending decades of bloody ethnic conflict in Sri Lanka.
But he then fell out with the government and unsuccessfully tried to oust Mahinda Rajapaksa, the president, in the January 2010 presidential elections.
After being jailed, he won a seat in the following parliamentary elections which were won by Rajapaksa's party.
Fonseka was arrested two weeks after his defeat in the polls and is serving a 30-month jail term.
He has said the government is seeking revenge for his decision to stand against the president.
Fonseka has also angered the government by saying he would testify before any international war crimes tribunal into Sri Lanka's separatist war.