India vows justice after deadly 'terror' car blast that killed 12 people

India's government on Wednesday vowed to bring the "perpetrators, their collaborators, and their sponsors" of a deadly car blast in the heart of the capital New Delhi to justice and called it an act of terrorism".

The powerful blast on Monday killed at least 12 people and wounded 30 others, according to hospital officials.

It was the most significant security incident since April 22, when 26 mainly Hindu civilians were killed at the tourist site of Pahalgam in Indian-administered Kashmir, triggering clashes with Pakistan.

"The country has witnessed a heinous terror incident, perpetrated by anti-national forces, through a car explosion near the Red Fort", a cabinet statement read, after a meeting chaired by Prime Minister Narendra Modi.

It was the first confirmation that India is treating the blast as an act of terrorism. 

The historic Red Fort in the crowded Old Delhi quarter of the city is one of India's most well-known landmarks, and the site of the annual prime minister's Independence Day speech.

The cabinet expressed "profound grief" over the loss of lives.

It did not give further details of who might have been behind the attack, but said India would maintain a policy of "zero tolerance towards terrorism in all its forms".

It condemned what it called a "dastardly and cowardly act that has led to the loss of innocent lives".

Ritu Saxena, the chief medical officer of Delhi's LNJP hospital, told AFP earlier on Wednesday that "12 people have died and more than 30 are injured". 

Witnesses described to AFP how the car exploded in traffic and how people caught up in the surge of flames were set on fire.

The 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 the jihadist group Al-Qaeda.

Both groups are listed as terrorist organisations in India.

The government ordered an investigation with the "utmost urgency" so that "the perpetrators, their collaborators, and their sponsors are identified and brought to justice without delay."

India's National Investigation Agency is leading the probe into the explosion.

The government added India's "steadfast resolve to safeguard the lives" of all its citizens, consistent with "its enduring commitment to national security".

It also thanked foreign governments for messages of solidarity.

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".

India rejected the "baseless and unfounded" allegations made by an "obviously delirious Pakistani leadership".

The Islamabad attack was claimed by a faction of the Pakistani Taliban.

US Secretary of State Marco Rubio said he spoke about the Delhi blast on the sidelines of a Group of Seven meeting in Canada with his Indian counterpart Subrahmanyam Jaishankar.

Asked if the attack could re-inflame tensions with Pakistan, Rubio told reporters: “We're aware of the potential that holds. But I think the Indians need to be commended. They've been very measured and cautious and very professional in how they're carrying out this investigation.”

“It clearly was a terrorist attack, and was a car loaded with highly explosive materials that detonated and killed a lot of people.”