Four people have been arrested on suspicion of facilitating a suicide bombing that killed more than 30 people on Friday, Pakistan's interior minister has said.


Mohsin Naqvi said an Afghan national who is alleged to be the mastermind behind the attack was among those detained. One counter-terrorism officer was killed and three more were wounded in the raids to arrest the suspects, he added.


The Islamic State group has claimed responsibility for the bombing that targeted Friday prayers at the Shia mosque in the Tarlai area, when it was packed with worshippers.


More than 160 people were injured in the blast, which was the deadliest in the capital for more than a decade.


Huge crowds were seen in the city on Saturday, as thousands of mourners gathered for the funerals of the bombing's 32 victims. Funeral prayers took place amid tightened security, with soldiers standing guard and police checkpoints set up in key areas.


Ashiq Hussain, who lost his 21-year-old nephew Mujtaba Ali in the attack, told the Reuters news agency his family was broken.


Condemning the attack on Friday, Pakistan's Prime Minister Shehbaz Sharif expressed deep grief. The country's President, Asif Ali Zardari, said targeting innocent civilians is a crime against humanity. Eyewitnesses and survivors of the blast have described moments of terror as bodies lay everywhere.


Naqvi accused India of funding those behind the attack and giving them targets. The Indian foreign ministry has condemned the bombing, and dismissed accusations of its involvement as baseless. Pakistani Defence Minister Khawaja Asif suggested Afghanistan could have been involved, prompting a response from the Afghan Taliban government, which called his comments regrettable.


Naqvi has pledged to enhance security in Islamabad, planning to recruit thousands of new police officers and improve smart security systems in the city.


Although attacks in the capital are relatively rare, the recent week has seen heightened violence, with 58 civilians killed in coordinated attacks in Balochistan province. The Balochistan Liberation Army has claimed responsibility for these attacks, while military operations have reportedly killed over 200 militants in response.