The threat from them is pretty high, he told PTI against the backdrop of the July 13 Mumbai blasts in which 22 people were killed.
"Pretty high. They are no longer fledgling outfits. They have established several modules and they have gained expertise in assembling bombs and transporting bombs," he said.
Chidambaram was asked how serious was the threat from home grown terrorists like Indian Mujahideen.
Asked whether there was a needle of suspicion pointing at IM in the recent Mumbai blasts, he said, "no. I have said they (Mumbai Police) have not shared any details and I am not in a position to share any details." He said the last reports he got was that Mumbai Police''s Anti-Terrorist Squad (ATS) has some good leads.
"Since they have not shared any more details, I am in no position to share any details," he said.
Asked if there are any suspects, he said, "there are good leads." To a question whether the July 13 blasts blotted his record, he said there have been two blasts in Pune in 2010 and in Mumbai a fortnight ago.
"Both are setbacks. Both are terrorist incidents undoubtedly. And therefore, to the extent that the Government of Maharashtra could not prevent them and to the extent that the Government of India could not help the Government of Maharashtra to prevent them, is a negative on our record as opposed to the many positives that are on record," he said.