American Marconi Wireless News - Indian PM calls deadly Delhi blast 'conspiracy'

Police are yet to give exact details of what caused Monday's blast near the historic Red Fort, one of India's most well-known landmarks, and the site of the annual prime minister's Independence Day speech.

It is the first 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.

"I assure everyone that the agencies will get to the bottom of the entire conspiracy," Modi said, in a speech during a state visit to neighbouring Bhutan, without giving further details.

"All those involved will be brought to justice."

At least 19 people were also wounded when flames ripped through several vehicles. Crime scene investigators scoured through the wreckage early on Tuesday.

The explosion on Monday 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.

Defence Minister Rajnath Singh, speaking at a conference in New Delhi, said that investigative agencies were "conducting a swift and thorough inquiry" and that the findings "will soon be made public".

Singh, echoing Modi's words, said "those responsible for this tragedy will be brought to justice, and will not be spared under any circumstances."

Senior Delhi police officer Raja Banthia said they were investigating the blast in the crowded Old Delhi quarter of the city, under anti-terrorism laws.

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 on Tuesday that the death toll had risen to 12, although that figure has not been confirmed.

- 'People were burning' -

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

"I saw the car explode while it was moving," said Dharmindra Dhaga, 27.

"People were on fire and we tried to save them... Cars and people were burning -- people inside the cars were burning," he said.

"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.

A woman broke down outside the ward where her husband was being treated.

New Delhi accused Pakistan of backing the gunmen after the April attack in Pahalgam, a claim 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.

The last significant attack in the Indian capital was in September 2011, when a bomb hidden in a briefcase ripped through a crowd outside New Delhi's High Court, killing at least 14 people.

D.Moore--AMWN