Protesters in Bangladesh torch headquarters of state broadcaster BTV

Protesters set fire to the headquarters of Bangladesh's main state broadcaster BTV with "many people" trapped inside its offices, the network has said.

An official at the station, speaking to AFP on condition of anonymity, said on Thursday that hundreds of protesters had stormed the premises, setting alight at least 60 vehicles and an office building.

"They first torched a police post at Rampura after police opened fire at them," he said, referring to a neighbourhood in the capital Dhaka.

"They chased the police officers when they took refuge at the BTV office. Angry protesters then caused mayhem here."

A post on BTV's verified Facebook page said the fire was "catastrophic" and "spreading fast".

"We seek the cooperation of the fire service. Many people are trapped inside," the broadcaster said.

Bangladesh's police force has this week stepped up a violent crackdown on weekslong student protests demanding reforms to civil service hiring rules.

At least 32 people have died in the clashes so far this week.