New Delhi, Dec. 29: A sacked air force official has been arrested from Punjab on charges of sharing secret documents with operatives of Pakistan spy agency ISI.

Ranjith K.K. was dismissed hours before he was picked up from the Bhatinda Air Force Station yesterday by a joint team of military intelligence, the air force and Delhi police's crime branch.

Union home ministry sources said 12 serving and retired defence personnel had been arrested in the past three years for allegedly spying for the ISI or being part of its espionage racket.

The action against Ranjith, a Kerala native, follows the arrests last month of five persons, including a former army man and a serving BSF constable, for allegedly passing defence inputs to the ISI. Around the same time, an alleged Trinamul student union leader was among four of a family held in Calcutta on charges of supplying naval secrets to Pakistan.

In the latest case, the Delhi police had kept an eye on Ranjith after being tipped off that some defence personnel had been drawn into spying rings through honeytraps.

"Ranjith allegedly passed on information pertaining to a recent air force exercise, movements of aircraft and deployment of units. In return, he received monetary benefits in his bank account," Delhi police joint commissioner Ravindra Yadav said.

Ranjith had joined the air force in 2010 and was posted at Bhatinda as lead aircraft man, or LAC. Another Delhi officer said Ranjith had been lured by an unidentified woman he had met on a social networking site.

"He had received a few VOIP calls (Internet-based calls that make tracing the source difficult) on his mobile in which the caller, a woman with British accent, introduced herself as Damini McNaught and posed as an executive of UK-based news magazine. She interviewed Ranjith and assigned him the task of getting the information. She deceived him by saying the information would be published and he would get monetary benefits," the officer said.

Sources said Ranjith came in touch with the purported woman on Facebook while recovering from an illness in a military hospital in September. "The lady contacted him on Facebook and he reciprocated," the source said.

Ranjith came under the scanner of the air force's intelligence wing because of his "unusual activity", the sources said, adding he had shared sensitive details of a base from where drones and airborne early warning and control systems are operated.

The investigators are probing whether Ranjith, brought to Delhi today, is linked to the five held last month and their suspected ISI-backed ring.