May 12 (Bloomberg) -- Sri Lankan President Mahinda Rajapaksa said his party's election win in Eastern Province, almost a year after the army seized the region from rebels, is a ``mandate'' to drive the Tamil Tigers from their last strongholds in the north.

The United People's Freedom Alliance won 20 of the 37 seats in the provincial council in an alliance with the Tamil Makkal Viduthalai Pullikal, a party comprising of defectors from the Liberation Tigers of Tamil Eelam.

``The people of the east have given a clear mandate of peace through the defeat of terrorism,'' Rajapaksa said in a statement yesterday. Opposition parties accused armed groups of threatening voters.

LTTE fighters were driven from Eastern Province by security forces last July in the worst defeat in their 25-year insurgency to establish a homeland in the South Asian island's east and north. The army is staging almost daily attacks on the LTTE bases in the north.

Voters in Batticaloa, Ampara and Trincomalee districts elected members of the Eastern Provincial Council two days ago after choosing nine local councils in the area in March. The TMVP, the pro-government breakaway faction of the LTTE, won control of eight local councils in the March balloting.

The opposition United National Party and its allies in the Sri Lanka Muslim Congress won 15 seats in the May 10 ballot. Two smaller parties won a seat each. The Tamil National Alliance, the main Tamil party, boycotted the vote.

Flawed Vote

The opposition condemned the vote as flawed. ``We will challenge the verdict as this is daylight robbery,'' Muslim Congress head Rauff Hakeem said in a telephone interview from the capital, Colombo. ``We are approaching the Election Commissioner to tell him about the systematic rigging that was openly done.''

The opposition is planning to meet in Colombo ``in a couple of days'' to decide on whether to start legal action to try to overturn the result, Hakeem said.

Turnout of 60 percent of the 1 million registered voters was a ``great success,'' Foreign Minister Rohitha Bogollagama said in the U.K. yesterday, according to the Defense Ministry's Web site.

Terrorist Group

The government's power-sharing plan is based on a 1987 constitutional amendment that provides for establishing provincial councils in the north and east. The LTTE, which is designated a terrorist organization by the U.S., the European Union and India, rejected the plan in 1988 saying too much power was left with a national parliament.

Eastern Province, which accounts for 15 percent of Sri Lanka's land area and 7.9 percent of its population, contributed less than 5 percent of gross domestic product during its occupation by rebels, according to Sri Lanka's central bank.

The government is seeking $1.8 billion in aid to rebuild the province and bring investment and tourists to the region that has a 426-kilometer (265-mile) coastline.

The army's activities in the east are making refugees of the Tamil people, Mavai Senathirajah of the TNA, which holds 22 seats in the 225-member national parliament, said last week.

``For 18 years there was agreement that the merger of the northeast, the habitat of the Tamil people, must be the cornerstone for a resolution to the conflict,'' he said. ``The government is dividing the north and east for its political gains. The election will worsen the ethnic problem.''

Armed groups aligned with the government threatened supporters, Senathirajah said before the ballot.

Tamils make up 11.9 percent of Sri Lanka's 20 million people and Sinhalese almost 74 percent, according to a 2001 census. Muslims make up about 8 percent.

In Eastern Province, Tamils make up 44.3 percent of the population with Muslims 32.6 percent and Sinhalese 22.6, according to the state-run Daily News newspaper.

To contact the reporter on this story: Michael Heath in Sydney at mheath1@bloomberg.net.

Last Updated: May 12, 2008 01:15 EDT