Security forces have killed at least 39 suspected militants in nationwide operations following a suicide attack at a Sufi shrine in southern Pakistan.

The terrorist attack was claimed by the Islamic State group, which said it targeted a Shiite gathering.

Three security officials said the overnight raids on militant hideouts also led to the arrest of 47 suspects, including some in Sindh province where the attack on the shrine happened on Thursday.

A suicide bomber walked into the Lal Shahbaz Qalandar shrine in Sehwan and detonated his explosives among a crowd of worshippers, killing 75 people. Dozens of others were injured in the blast.

The attack - the country's deadliest in years - stunned the nation and raised questions about the authorities' ability to combat militant groups despite several military offensives targeting insurgents.