Home Minister P Chidambaram said Indian investigators will on Monday question David Coleman Headley, arrested by the Federal Bureau of Investigation (FBI) for allegedly plotting terror attacks in India on behalf of the Pakistan-based Lashkar-e-Taiba (LeT).
Indian intelligence agencies suspect a bigger plot was being hatched by Headley and his associates owing to his links with militants in Pakistan.
Chidambaram said: "We know Dave Headley visited Pakistan on several occasions. Most of the times he seems to have travelled in his own name under a passport bearing his name. Now who his friends were, who is he acquainted with - these are matters which are to be investigated."
"Our investigators are joining the probe in the United States. Our investigators will reach the US by Sunday and join the investigation on Monday," Chidambaram told reporters in New Delhi on Friday while presenting his ministry's annual report.
Headley has reportedly told the FBI that their target was a prominent actor Rahul.
When asked about the identity of Rahul, Chidambaram said, "It's not the Rahul that you and I think it is. It could be a code name and could have different interpretations. It doesn't mean the name that you and I know."
The FBI on Tuesday said the LeT, blamed for the 26/11 Mumbai terrorist attack, was planning to use an American national to carry out another major terror strike in India.
Headley was arrested early this month at Chicago's O'Hare international airport before boarding a flight to Philadelphia, intending to travel on to Pakistan.
According to the FBI affidavit filed in a Chicago court, Headley was in close contact with Ilyas Kashmiri and several unidentified leaders of LeT.
Kashmiri, the operational chief of Pakistan-administered Kashmir section of Harakat-ul Jihad Islami (HUJI), a Pakistani-based terrorist organisation with links to Al-Qaeda, is presently believed to be in Pakistan's restive Waziristan tribal region.
Intelligence agencies including the Research and Analysis Wing (RAW) and the Intelligence Bureau are also probing the possibility of a similar recce being carried out by British or American nationals on behalf of the LeT in Mumbai before the 26/11 attack.