Pokhran, in Rajasthan, witnessed the Indian Air Force's combat and fire prowess when 'Iron Fist', one of the biggest exercises by the IAF, was conducted.
An official in the Home Ministry is being questioned about sharing confidential information with Pakistan.
Sources say the man was in touch with Sumaar Khan, a computer expert who was arrested last month by the Rajasthan Police for allegedly sharing important details with Pakistan's Inter-Services Intelligence (ISI) about the "Iron First" exercise conducted recently by the Indian Air Force along the border in Pokhran.
The exercise, in which the Air Force demonstrated its full combat and fire power, was witnessed by President Pranab Mukherjee, Prime Minister Manmohan Singh, and Defence Minister AK Antony.
Rajasthan Police had said that Mr Khan passed information to Islamabad "related to Indian defence installations and military activities."