Delhi Police said 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)," Special Cell's Special Commissioner M.M. Oberoi told IANS.

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

Oberoi also said that 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 the information and documents with two Pakistani agents who chatted with him on social media site Facebook pretending to be women.

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

According to the Special Cell's officers, a few months ago, the officer befriended on Facebook the ISI agents, who posed as women models.

"They chatted regularly on WhatsApp... and also allegedly exchanged intimate messages," the officer said, adding after gaining Marwaha's trust, the "Pakistani agents asked the officer for classified documents".

He 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.