Pakistan political tensions
At least 20 people dead and another 50 injured as Shia mosque attacked in Shikarpur, police said Mohsin Raza/Reuters

A terror group linked to Islamic State (Isis) has claimed responsibility for an attack at a Shia mosque that killed at least 31 people in Pakistan.

The blast occurred during Friday prayers (30 January) in Shikarpur, southern Pakistan, police said.

Another 50 people were injured during the blast.

The Jundullah group, which last year pledged allegiance to IS, said the attack was carried out as Shia Muslims are "enemies".

"Our target was the Shia community [mosque]... They are our enemies," Fahad Marwat, a Jundullah spokesperson, was quoted by Reuters as saying.

Jundullah is an Islamist group also associated with Tehrik-i-Taliban Pakistan (TTP) which, in December 2014, attacked a school in Peshawar, killing hundreds of children.

It is not yet clear what caused the explosion and police are investigating.

Deputy Commissioner Shikarpur Hadi Zardari told IBTimes UK more than 100 people were present in the mosque when the explosion took place and an unspecified number of victims were trapped under debris after the roof collapsed due to the blast.

"Police have not yet confirmed but its seem that was a suicide blast and suicide blew himself inside the mosque," Zardari said.

"Rescue workers have shifted more than 45 injured into Sukkur and Larkana district hospitals of Sindh province while 26 dead bodies were handed over to their relatives."

The remaining dead bodies are still in the hospitals.

Civil Hospital Shikarpur Superintendent Shaukat Memon told reporters children were among the dead and injured.

"The condition of more than 20 wounded is still critical and we are shifting them to District Headquarter hospitals for immediate surgery," Memon told.

This is the second attack on a Shia Muslim mosque in Pakistan this month. On 10 January, at least eight people were killed and another 16 injured following a blast in a mosque in Garrison city, in the Punjab province.

Pakistani Army spokesman Maj Gen Asim Bajwah claimed, in one of his latest interviews with different foreign media outlets, the military has successfully cleared the large parts of north Waziristan and Khyber Agency from terrorists and more than one thousand militants have been killed in the military operations.

Pakistan has also decided to ban Haqqani Network, an Afghan militant group that carried out attacks on US and Nato forces in Afghanistan and along the border with Pakistan.