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.

Announcing the arrests on Saturday, Naqvi accused India of funding those behind the attack and giving them targets. The Indian foreign ministry has condemned the bombing, and rejected accusations of its involvement as 'baseless'.

Pakistani Defence Minister Khawaja Asif on Friday suggested Afghanistan had been involved in the attack. The Afghan Taliban government described Asif's comments as 'regrettable', saying he alleged its involvement 'without presenting any credible evidence'.

Naqvi has pledged to increase security in Islamabad, including by recruiting thousands of new police officers and improving the city's smart security systems.

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'.

As thousands of mourners gathered for the funerals of the bombing's 32 victims, security measures were tightened in the city, with soldiers standing guard and police checkpoints established in key areas.

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