“All those involved will be brought to justice,” he said.
Indian authorities have stopped short of calling the blast an attack, saying they were awaiting forensic analysis.
The Home Affairs Ministry said that India’s anti-terrorism force, the National Investigation Agency, is leading the probe.
The Red Fort explosion came hours after Indian police said they had arrested a gang and seized explosive materials and assault rifles.
Police said the men were linked with Jaish-e-Mohammed, a Pakistan-based Islamist group, and Ansar Ghazwat-ul-Hind, a Kashmir offshoot of jihadist group Al-Qaeda.
Both groups are listed as terrorist organisations in India.
Home Minister Amit Shah, after chairing security talks following the blast, said he had instructed officials “to hunt down each and every culprit behind this incident”.
“Everyone involved in this act will face the full wrath of our agencies,” he added in a statement.
‘People were burning’
New Delhi’s deputy chief fire officer AK Malik told AFP shortly after the explosion that eight people had been killed.
The Press Trust of India news agency reported that the death toll had risen to 12, although that figure has not been confirmed.
Witnesses described to AFP how the car exploded in traffic and how people caught up in the surge of flames were set on fire.
“People were on fire and we tried to save them … Cars and people were burning – people inside the cars were burning,” said Dharmindra Dhaga, 27.
“I was telling the public to save them, rescue them, and get them out. The public was busy making videos and taking photos.”
The emergency ward at Delhi’s LNJP hospital was chaotic after the explosion as wounded people streamed in and doctors rushed to treat them.
In the attack in April in Pahalgam, Indian authorities were swift to accuse Pakistan of backing the gunmen – claims denied by Islamabad.
That attack sparked clashes between the nuclear-armed arch rivals in May, when more than 70 people were killed in missile, drone and artillery exchanges before a ceasefire was struck.
On Tuesday, after a suicide bomber in Islamabad killed at least 12 people, Pakistan’s Prime Minister Shehbaz Sharif blamed “terrorist proxies backed by India”.
He did not provide any evidence.
India said it rejected the “baseless and unfounded” allegations made by an “obviously delirious Pakistani leadership”.
Without directly referencing the Islamabad incident, foreign ministry spokesperson Randhir Jaiswal said in a statement that “it is a predictable tactic by Pakistan to concoct false narratives against India in order to deflect the attention” from its internal issues.
– Agence France-Presse
