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.
Attacks are relatively rare in the capital, although one in November left 12 dead and another 27 injured.
The blast on Friday comes after a week of violence which saw 58 civilians killed in coordinated attacks in the province of Balochistan.
The Balochistan Liberation Army (BLA) rebel group said it was behind the attacks. The military – which has been fighting an insurgency in the region for decades – said it had killed more than 200 militants in response.