Sri Lanka's president has confirmed a two-and-a-half-year jail term for former army chief Sarath Fonseka.

Sarath Fonseka was hailed as a hero for leading the army in last year's defeat of the Tamil Tiger separatists, which ended decades of civil war.

But he fell out with president Mahinda Rajapakse over who should take credit for the victory.

A court martial earlier this month found him guilty of making irregular military purchases at the height of the fighting.

A spokesman for the Sri Lankan government says the president has backed the sentence and it will begin immediately.

The former general's supporters maintain the cases against him are politically motivated.