A murder investigation has been opened into Bangladesh's ex-premier Sheikh Hasina over the police killing of a man during civil unrest, BBC reports.

Six other top figures in the previous government are also being investigated following weeks of deadly unrest in the capital Dhaka.

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Mamun Mia, a lawyer who brought the case on behalf of a private citizen, said the court in Dhaka had ordered police to accept "the murder case against the accused persons".

This is the first step in a criminal investigation under Bangladeshi law.

Hasina resigned and fled the country earlier this month, fleeing to neighbouring India, as calls grew for her to stand down.

More than 400 people were killed in weeks of student demonstrations culminated in the demands against Hasina.