Sri Lanka's main ethnic minority Tamil party has secured a landslide victory in a provincial poll.

The Tamil National Alliance, the former political proxy of the defeated Tamil Tiger rebels, won 30 seats in the 38-member provincial council in the former northern war zone, election officials said.

President Mahinda Rajapaksa's ruling coalition won seven seats, while a Muslim party won one.

It was the first provincial council election in the north in 25 years and was held after the government came under international pressure to restore democracy.

Defeat for the government, the most humiliating set-back for Mr Rajapaksa since he assumed office in 2005, is largely symbolic.

But the TNA's victory shows that the defeat of the rebels in 2009 did nothing to subdue calls for autonomy among Tamils, who make up about 14% of Sri Lanka's 20 million people.

The TNA won more than 84% of the votes in Jaffna.

Jaffna was once the heartland of the rebel movement.

The TNA won 81% of the vote in Kilinochchi, the de-facto capital of the separatists.

In Mullaitivu, they secured 78% of the vote where thousands of civilians were said to have been killed in May 2009, when government forces moved in to defeat the rebels.

The government has accused the TNA of renewing calls for a separate state through its push for devolution of power.

The TNA says it wants devolution in a united Sri Lanka, not a separate state.

"They must trust us," CV Wigneswaran, the chief candidate for the TNA who will be the province's chief minister told reporters.

"We are for an undivided Sri Lanka, where there is a certain amount of self-ruling under the federal constitution," he said.