Chief Metropolitan Magistrate Sanjay Khanagwal sent Ranjith K.K. to judicial custody after he was presented before him on expiry of his two-day police custody.
The court sent him to judicial custody after Delhi Police said he was not required for further custodial interrogation in the case.Ranjith, who hails from Kerala, was arrested last month from the Bathinda air base in Punjab on charges of spying for Pakistan's Inter-Services Intelligence, police said.
An IAF official said Ranjith, who was a Leading Aircraftman with the Indian Air Force, was dismissed last week after evidence was found against him that he shared sensitive information with others.
According to Delhi Police Crime Branch officials, who are probing the espionage racket since the arrest of some people earlier this month, they have shared information with the IAF about Ranjith's suspected links with the ISI.
Ranjith was the sixth person to be arrested by Delhi Police in the espionage racket.
Five other people, including a serving and a former army personnel and a serving BSF personnel, were arrested earlier this month.