Indian authorities said on Sunday that a deadly car blast in New Delhi last week was an attack carried out by a "suicide bomber," announcing the arrest of an accomplice.

The National Investigation Agency (NIA), the country's counterterrorism law enforcement body, said the alleged attacker and the second suspect were both from Indian-administered Kashmir, where police have carried out sweeping raids in recent days.

Announcing "a breakthrough" in the investigation, the NIA said in a statement it had arrested Amir Rashid Ali, "in whose name the car involved in the attack was registered."