Bangladeshi police shot and killed two people overnight during ongoing violent opposition protests against the first anniversary of Prime Minister Sheikh Hasina’s controversial re-election, a senior officer said Thursday.

Bangladeshi police shot and killed two people overnight during ongoing violent opposition protests against the first anniversary of Prime Minister Sheikh Hasina's controversial re-election, a senior officer said Thursday.

More than 5,000 supporters of besieged opposition leader Khaleda Zia attacked police with sticks in southern Noakhali district late Wednesday, forcing them to "open fire in self defense," the officer said.

"At least two people have died in the shooting. Eight police officers were injured," district deputy police chief S.M. Ashrafuzzaman told AFP. Local media said the victims were activists of the main opposition Bangladesh Nationalist Party (BNP).

The deaths brought the toll in the nationwide protests to six since Monday when Zia called on supporters to take to the streets nationwide against alleged vote-rigging at the January 5, 2014 polls.

Police confined Zia to her office in the capital for the sixth day Thursday in a bid to halt the rallies which include a blockade around the country of highways, railway lines and ports.

Police removed padlocks from the gates of her building in upmarket Gulshan district on Thursday, but were still patrolling the perimeter.

Zia has asked supporters to enforce the transport blockade indefinitely until the government is toppled and new multi-party elections organized.

Zia's 20-party alliance boycotted last year's polls which were marred by deadly violence, claiming that the outcome would be rigged.

Arch rival Hasina, in power since 2009, had refused to step down before the election so the poll could be organized by a neutral caretaker administration.

The boycott meant most members in the 300-seat parliament were returned unopposed, handing Hasina another five years in power.

Facing relentless protests to mark the anniversary in recent days, Hasina's government has threatened to bring murder charges against Zia for inciting violence.

Authorities have also launched a nationwide crackdown on the BNP, arresting its deputy chief and hundreds of its activists.

On Wednesday a court also banned all local media from reporting speeches made by Zia's exiled son and heir apparent of the party.

Zia's spokesman Shimul Biswas said the 69-year-old leader had fallen ill after police used pepper spray at her office on Tuesday when she tried to break free of her confinement.

"A doctor saw her on Wednesday. She is suffering from breathing problems. But she said the blockade will continue," he said.