Scores of polling booths were torched and a train set alight on the eve of Bangladesh's election Saturday as the opposition launched a strike against the vote "farce".

The Bangladesh Nationalist Party (BNP), which is boycotting the vote, called the two-day general strike -- but it has little chance of thwarting Prime Minister Sheikh Hasina's re-election in what is effectively a one-party contest.

The strike comes after BNP leader Khaleda Zia issued an appeal to voters to also "completely boycott" what she called "a scandalous farce", and accused the government of placing her under house arrest.

The build-up to Sunday's vote has been dominated by political violence, with around 150 people killed since the date was set in October.

Observers fear the contest will heighten tensions after Bangladesh endured its bloodiest 12 months since a brutal 1971 independence war against Pakistan.

One opposition activist was killed on Saturday in the northern town of Patgram during clashes with governing Awami League supporters, police said.

Officials also said that protesters had set fire to or attempted to torch scores of polling booths, with the private online newspaper Bdnews24 putting the number of burnt booths at more than 100.

Stacks of ballot papers were set alight by Islamists in another northern town, police said.

But the country's chief election commissioner Kazi Rakibuddin Ahmad said the attacks would not derail the polls and that alternative arrangements were being made in the affected areas.

"We are worried as you are about it," he said. "We've asked for strengthening law enforcement."

A group of BNP activists hurled a petrol bomb through the window of a train carriage in the northwestern town of Natore, injuring six passengers, police said.

Although the government denies Zia has been detained, dozens of riot police could be seen outside her home in Dhaka Saturday, along with water-cannon and sand trucks, preventing anyone from entering.

The BNP and 20 other parties are boycotting the polls after Hasina rejected their demands that it be overseen by a neutral caretaker government.

This weekend's strike is only the latest in a string of such protests, which have forced the closure of schools, offices and shops.

After frequent firebombings of vehicles, many people are too scared to leave home during the shutdowns.

Police say 1,200 opposition activists have been detained, although the parties say the actual number is much higher.

Troops in the streets

Around 50,000 troops have been deployed across the country in a bid to contain the unrest.

The United States, European Union and Commonwealth have refused to send observers to an election that the opposition says lacks any credibility.

The outcome is not in doubt as Awami League candidates or allies are running unopposed in 153 of the 300 parliamentary seats.

Hasina has rejected all demands for a postponement until there is consensus on the electoral framework.

Gowher Rizvi, her senior foreign policy adviser, said the government had to hold the elections as parliament's term had expired.

"If we had postponed them, there would have been a complete legal and constitutional vacuum," Rizvi told AFP, while admitting the BNP's boycott had robbed the poll of some of its "lustre".

Rizvi said the premier had made clear her desire to "engage in a constructive dialogue" with the BNP, although Hasina and Zia have a toxic relationship.

BNP vice chairman Shamsher Chowdhury said there could be no compromise on demands for Hasina to stand aside for fresh elections.

A poll published Friday showed the BNP would have narrowly beaten the Awami League and that 77 percent of voters are against the election.

Both sides have blamed each other for the latest unrest, which has pushed the death toll from political violence since the start of 2013 to more than 500, according to local rights activists.

Human Rights Watch, a New York-based advocacy group, said both sides shared responsibility for the chaos.

"The actions of Bangladeshi political leaders -- whether the government crackdown on the opposition or the opposition complicity in poll violence -- deprive the country's voters of any true choice," said the group's Asia director Brad Adams.

Some of the worst violence followed the conviction of leading Islamists for crimes in the 1971 independence war. The main Islamist party, Jamaat-e-Islami, has been banned from the polls.