Militants plan strike on India's N-facilities

Describing it as a "very serious threat," Narayanan identified Lashker-e-Taiba (LeT) as the group planning the strike.

"There is information that maybe one of our atomic energy installations could be the target," he told CNN-IBN news channel.

"It's (an) LeT operation... it is a very serious threat," he said.

India has pointed a finger at the LeT -- a rebel group active in the restive Himalayan region of Kashmir -- for a series of bomb attacks on commuter trains in India's financial hub of Mumbai on July 11 that killed 183 and wounded more than 800.

The group however has denied responsibility for the Mumbai blasts.

New Delhi also blames the LeT for a deadly attack on its national parliament complex in December 2001 that brought India and Pakistan to the brink of their fourth war.

New Delhi blames Pakistan for arming and training Islamist rebels fighting Indian rule in the Himalayan region, which has triggered two of the three wars between the nuclear-armed rivals.