In a major security lapse, a man posing as a Major General, gained entry into the city's sensitive Fort William, which headquarters the army's Eastern Command, and was later arrested while clicking photographs.
The suspect, identified as P K Mitra, was arrested after suspicion aroused as he took pictures of the premises.
He is being questioned by a joint team of local police, military intelligence and central security agencies to find out whether he was a spy or not.
"He was suspected to be an impostor and when questioned by security, he was found to be fake. He was later handed over to the police", an army source said.
The Eastern Command is one of the seven operational commands of the army.
It is responsible for defending the sensitive northeast and eastern parts of the country.
