Delhi Police on Friday said it has arrested Indian Air Force (IAF) Group Captain Arun Marwaha on charges of espionage for passing secret information to Pakistan's Inter-Services Intelligence (ISI) agency.

"He was arrested on Wednesday after a case was registered against him under the Official Secrets Act (OSA)," Delhi Police Special Cell's Special Commissioner M.M. Oberoi told IANS.

He was produced before a court on Thursday that sent him to police custody for five days.

Oberoi also said Marwaha was earlier detained by the IAF in January.

The Group Captain had been detained by the IAF for investigation on January 31 after his activities were found "suspicious". The Air Force had approached the Delhi Police to investigate the case.

According to a Special Cell officer, privy to the investigation, Marwaha, 51, shared information and documents with two Pakistani agents who chatted with him on social media site Facebook, pretending to be women. The fake accounts, in the names of 'Kiran Randhwa' and 'Mahima Patel', were used to entice him.

He allegedly used his smartphone to click pictures of the classified documents pertaining to the IAF headquarters and then sent them across via WhatsApp.

According to the Special Cell's officer, the officer befriended the ISI agents posing as women models a few months ago.

"They chatted regularly on WhatsApp... and also allegedly exchanged intimate messages. The ISI agents also honey-trapped him after obtaining some of his nude pictures," the officer said, adding that after gaining Marwaha's trust, the "Pakistani agents asked the officer for classified documents".

"The documents which Marwaha shared mostly dealt with training and combat related air exercises. We also found he shared documents of 'Gagan Shakti', an exercise," the officer added.

Marwaha is being questioned at the Special Cell's headquarters in Lodhi Colony area of south Delhi.

The police are also probing if he had any accomplices.

According to informed sources, Marwaha's phone has been seized and sent for forensic examination.

"He has even confessed to have had access to many secret documents and plans due to his posting at the Air Force Headquarters in Delhi."