Authorities in Bangladesh say security forces have surrounded a house where they believe the leader of a militant Islamist group is hiding.

At least 500 police are involved in Wednesday's operation in the northeastern city of Sylhet. Officials say they have cordoned off the suspected hideout of Shaikh Abdur Rahman, head of the banned group Jamayetul Mujahedin Bangladesh.

The militant Islamist group has been blamed for a wave of bombings that have killed at least 28 people since August.

A Bangladeshi court sentenced Rahman in absentia last month to 40 years in prison for his involvement in the murder of two judges.

More than four-fifths of Bangladesh's population is Muslim, but the nation is a secular parliamentary democracy. Rahman's group wants the government to adopt strict Islamic law as its legal code.

Some information for this report was provided by AFP, AP and Reuters.