Lawyers in Nigeria have lodged a claim for $1.2m (£870,000) in damages against the security officers on behalf of a Yoruba separatist militant, Sunday “Igboho” Adeyemo.
The police raided his home on Thursday, allegedly killing some of his followers.
He leads a group calling itself Yoruba Nation, which campaigns for a breakaway state in south-west Nigeria.
The police accused him of stockpiling weapons.
Authorities have begun a clampdown on the secessionist group in an area that includes Nigeria’s biggest city, Lagos, banning them from holding a rally.