DHAKA: Opposition activists in Bangladesh trying to enforce a transport boycott threw petrol bombs at a bus early on Tuesday setting off a fire that engulfed the vehicle killing seven people, a fire department officer said.

The opposition rejected a general election just over a year ago and stepped up its protests last month in a bid to force Prime Minister Sheikh Hasina to step down and hold a new election.

At least 51 people have been killed in political violence over the past month including the seven on the night-bus to Dhaka.

“Seven died on the spot after opposition activists hurled petrol bombs,” fire department official Monir Hossain told reporters in the southeastern district of Comilla.

Sixteen people were injured, several of them critically, he said.

Spokesmen for the opposition Bangladesh Nationalist Party (BNP) were not available for comment. They routinely reject accusations that their activists are responsible for violence.

Bangladeshi politics has been mired for years in bitter rivalry between Hasina and BNP leader Begum Khaleda Zia.

Both women are related to former national leaders and they have alternated as prime minister for most of the past two decades.

Analysts say the renewed political turmoil could threaten the country's $24-billion garment export industry, already under pressure after a string of fatal accidents.