New Delhi, Feb 14: Two people could have executed the bomb attack on the Israeli embassy car, one who planted the device and the other who triggered it, sources among investigators said Tuesday. They did not rule out the possibility of an Indian Mujahideen hand in the terror strike.

The sources admitted that investigators still have no clue about the explosive used in the blast in the heart of the Indian capital that injured four people, including the wife of an Israeli diplomat.

A forensic sciences laboratory report expected by Wednesday would help investigators know the exact nature of the explosive used in the sophisticated magnetic bomb, the first of its kind used in India, they said.

But it was almost certain that a remote device, like a cell phone, could have been used to trigger the blast after a motorcyclist attached the explosive device that blew up the car.

This meant that two people were needed to execute the attack, one who planted the bomb and made a quick getaway and the other who triggered it, the sources said.

There is only a remote possibility that a timer device was used as it was a sticky bomb, the sources added.

Home ministry officials speaking on condition of anonymity said investigators were not ruling out any possibility and were, in fact, working on every possible angle to crack the blast case.

They said some Indian Mujahideen operatives, arrested in the past couple of months, were being questioned afresh to know if they have any link with the terror strike targeting Israelis in India.

Though the officials said the fresh interrogation was a routine exercise as happens after every attack, it does indicate that the Indian Mujahideen hand in the blast is also being suspected.

They said that Indian Mujahideen link is being looked into as investigators were working on a theory that home grown terrorists sympathetic to the Palestinian cause could also be involved.

The sources also said that intelligence reports suggest that some 40 Indian Mujahideen operatives were still active in various parts of the country, though many of their modules have been busted in the past couple of months.

Delhi Police's Special Cell, which is spearheading the investigation, is also examining the CCTV footage to get some clues about the biker and his bike.

"We are searching for the biker and are going through the CCTV footage to get more clues," said Dharmendra Kumar, Special Commissioner (Law and Order), Delhi Police.

Police have also launched search operations in some Delhi hotels, particularly in Paharganj area near the New Delhi Railway Station.

The National Investigating Agency (NIA), India's premier anti-terror probe agency, is likely to join the probe into the Monday bombing.

A NIA team Tuesday morning took a look at the blast site and the Israeli embassy car that was badly damaged in the attack.

NIA director S.C. Sinha was also present at the Aurangzeb Road crossing where the blast took place Monday afternoon after a lone biker planted an explosive to the rear door of the Innova car from the Israeli embassy and sped away.

Two passengers in a red Indica were also affected by the blast.

Sinha declined to divulge any details of the probe so far. All he said was the NIA was ready to join the probe if Delhi Police sought their assistance.

"Delhi Police are investigating the case and we will assist them if we are asked for assistance."