Bangladesh forensics police investigate the site where a blogger was hacked to death. May 12, 2015.

Bangladeshi authorities moved to outlaw the ultra-hardline group Ansarullah Bangla Team (ABT) on Tuesday, after it was accused by the country's interior ministry of attacking and killing three secular bloggers earlier this year, the BBC reported.

The brutal attacks -- all carried out in broad daylight in busy streets --, prompted mass protests by freedom of speech activists, who have accused officials of complacency over the violence directed at the country's secular journalists and writers.

Preliminary investigations by police last week, however, revealed the involvement of the ABT in all three murders.

The ABT is now the sixth Islamic group to be outlawed in Bangladesh.