At least 10 people were killed in overnight violence as Bangladesh went to the polls for local elections, seven of them shot dead by security forces, police said Wednesday.

Much of the violence was in the southern coastal town of Mathabria, where clashes broke out when thousands of ruling party supporters attacked police and border guards taking ballot boxes to the government headquarters.

"A magistrate ordered the shooting and officers fired at thousands of unruly people who attacked us with machetes, rocks and sticks," district police chief Walid Hossain told AFP.

"Three people died on the spot and two on the way to hospital," he said, adding that another five people were injured in the police shooting.

Another police official said all the victims were supporters of the ruling Awami League who had apparently attacked police fearing a local loss for their party.

Security forces also shot and killed two people in the southeastern coastal town of Sabrang when supporters of a rebel ruling party candidate tried to snatch ballot boxes from the paramilitary forces, local police chief Kabir Hossain told AFP.

Three more died in other parts of the country as voting began Tuesday in the elections for more than 6,000 local council across the country.

The opposition Bangladesh Nationalist Party (BNP) has said almost all the local council polls were marred by violence, rigging and fraud including ballot-stuffing by the ruling party supporters.

The elections will be held in six phases over the next four months.

They will not change the political landscape of the country, but a sweeping victory would consolidate Prime Minister Sheikh Hasina's hold on power ahead of the general elections in 2019.

Local newspapers said Hasina's Awami League had won more than two thirds of the councils in the first round of the polls.