An explosive device has been made safe in a flat in St Petersburg by Russian police, three days after a bomb on the city's metro left 14 people dead, BBC News reports.

A city official said several suspects were detained after police raided the flat early on Thursday morning, Ria Novosti reported.

Neighbours were moved away and witnesses said three men were led out in handcuffs, the agency said.

The main suspect in the metro bombing, Akbarzhon Jalilov, died in the attack.