The Special Task Force (STF) of the UP Police arrested Sunit Kumar from Kangra district in Himachal Pradesh on Friday, an STF spokesman said in Lucknow.
Mr Kumar, posted at Babina Cantt in Jhansi, was arrested by the STF with the help of Military Intelligence and was brought to Meerut.
Mr Kumar was an aide of ISI agent Asif Ali who was arrested from Delhi Gate area in Meerut on August 16, the spokesman said.
"A laptop, hard disk, two mobile phones, and a pen drive were recovered from his possession," he said.
During interrogation, Mr Kumar said some three months before joining the army in December, 2012, he came in contact with a woman of foreign origin, the spokesman said.
Mr Kumar said after he joined the army the woman started taking information related to his unit as well as other units. He gave her a number of a unit.
He said the laptop recovered from him was provided by the woman through Asif.
On August 16, Asif was arrested from Meerut on the charge of passing defence information to the ISI.