The Sri Lankan military says it's ended its biggest ever offensive against the Tamil Tiger rebels.

The operation that the army code-named Sure Victory was launched in May last year, and cost many hundreds of lives on both sides.

It was aimed at capturing a seventy-five kilometre stretch of highway from the rebels and opening a vital land route to the Jaffna peninsula in the north of the country.

However the Tigers still hold more than a-third of the highway, forcing the government to supply its forces in Jaffna by expensive and dangerous sea and air routes.

The announcement of the end of the operation came as the Defense Ministry said the security forces had captured the small town of Oddusudan.