The national investigation agency will in all likelihood take over investigation into the Israel embassy blast case on Tuesday. Officials told News18 that the ministry of home affairs is issuing orders for the same. "We are expecting the orders shortly, will register a case as soon as they are received," an official said.

Iranian hand in the blast has emerged as the main line of investigation. Officials are also looking at the incident in Paris where a suspicious object was found outside the Israel embassy complex. "There are international ramifications of this case," an officer explained about why an NIA investigation is being sought in this matter.

Top intelligence sources on Sunday said evidence suggests that the explosion was a serious blast gone wrong.

Police had recovered battery remains from the Israel embassy blast site though most of the CCTV cameras near the site of the explosion were "non-functional" at the time of incident.

"We have recovered some CCTV footage but have not obtained anything concrete yet as most of the CCTV cameras in the area near the embassy are non-functional," an official source said. Earlier, footage retrieved from CCTV cameras showed a vehicle moving suspiciously near the embassy just before the explosion, sources said.

The minor IED blast took place near the Embassy of Israel on Friday evening, 40-50 metres away at Jindal House.

A team of National Security Guard also visited the explosion site on Saturday afternoon.

After initial investigation on Friday, the police had suspected a vehicle borne bomber of dropping or throwing the IED near a flower pot. But the recovery of the battery and initial reports about the kind of explosive used have forced investigators to look at the angle of a "well planned, well timed conspiracy."