A Delhi court on Saturday sent three doctors and a preacher, arrested in connection with the Red Fort blast, to 10 days' judicial custody.

All four accused, identified as Muzammil Ganaie, Adeel Rather, Shaheena Saeed and Maulvi Irfan Ahmed Wagay, were produced before Principal and Sessions Judge Anju Bajaj Chandna, who ordered their 10-day judicial custody.

The National Investigation Agency has so far arrested seven persons in the case, which is linked to a "white collar" terror module busted by the Jammu and Kashmir Police.

"The agency continues to pursue various leads in connection with the suicide bombing, and has been conducting searches across states in coordination with the respective police forces in a bid to identify and track others involved in the gruesome attack," the NIA said in a statement.

Dr Umar-un-Nabi, who was driving the explosives laden i20 car that detonated outside the Red Fort, had allegedly bought the vehicle in Ali's name.

Wani was arrested after it emerged that Umar had been trying to "brainwash" him into becoming a suicide bomber, officials said.

He was not persuaded but is alleged to have agreed to participate as an overground worker for the banned terror outfit Jaish-e-Mohammed.

PTI had earlier reported that the sophisticated terror module, spearheaded by a group of doctors, had been actively scouting for a suicide bomber since last year, with Umar being the alleged key planner.

Officials said Adeel's interrogation indicated that Umar was a "hardcore radical" who maintained that a suicide bomber was essential for their operations.

Following this disclosure, Srinagar Police sent a team to Qazigund in south Kashmir and detained Wani.

Wani allegedly admitted during questioning that he had met the "doctor module" in October last year at a mosque in Kulgam, Kashmir, the officials said.