There are fears allegations of vote rigging could provoke violence

Military officials have dismissed fears the army could influence the vote, saying troops are being deployed only at the request of civilian authorities.

A BBC correspondent says the risk of unrest is felt to be greatest in the southern province of Sindh and the North West Frontier Province.

The parliamentary polls on 18 February are seen as test of democracy.

President Pervez Musharraf called the election amid intense pressure from Western allies to restore democracy in Pakistan.

Parties loyal to him will face a range of opposition groups at the ballot box.

Balochistan blast

Sindh province is a stronghold of the Pakistan People's Party (PPP), which was led by former Prime Minister Benazir Bhutto until her assassination in December.

According to the BBC's M Ilyas Khan in Karachi, the province may see violence if the polls are felt to have been rigged by the government.

The province's home minister, Akhtar Zamin, said 26 Pakistani army battalions had begun deploying there.

Violence is also feared in the North West Frontier Province, bordering Afghanistan.

Eighteen of the province's 24 districts have been declared sensitive.

A local official said more than 50,000 police would be sent there for the elections.

At least nine people were meanwhile hurt when a bomb was detonated near the office of an election candidate in the south-western province of Balochistan.

The candidate himself was said to have been unhurt.

Balochistan already has a heavy military presence, having been the focus for several years of a nationalist insurgency.