An explosion claimed by militant group Islamic State ripped through a Muslim shrine in southwestern Pakistan on Saturday, killing at least 52 people and wounding scores, officials said.

The blast occurred at the Shah Noorani shrine, located in Balochistan province, about 100 kilometres north of the port city of Karachi. It took place while hundreds of people were inside, said Hashim Ghalzai, a local district commissioner.

Provincial Home Minister Sarfaraz Bugti said 52 people were killed and Ghalzai said more than 105 were wounded.

Islamic State said in a statement via its Amaq news agency that its fighters had carried out Saturday's bombing.

The government dispatched 25 ambulances from Hub to the shrine, said Akbar Harifal, provincial home secretary for Balochistan.

"Every day, around sunset, there is a dhamaal (ritual dance) here, and there are large numbers of people who come for this," said Nawaz Ali, custodian of the Sufi shrine.


Staff members of a local hospital wait for casualties of bomb blast at a Sufi shrine, in Karachi, Pakistan, Saturday. (Fareed Khan/Associated Press)

Balochistan has seen some of the worst militant attacks this year in Pakistan, one of which was claimed by an Islamist movement that is allied to the Islamic State group.

The province is also key to a $46-billion transport and trade corridor between Pakistan and China, which hinges on a deep-water port in the southwestern city of Gwadar.