The National Investigation Agency has arrested a key accused in the Visakhapatnam espionage case for his alleged involvement in snooping and working for Pakistan's spy agency Inter-Services Intelligence, an official said on Tuesday.

Giteli Imran, 37, a resident of Gujarat's Godhra, was arrested on Monday in connection with the case registered under sections of the Indian Penal Code, the Unlawful Activities (Prevention) Act and the Official Secrets Act, the NIA official said.

The National Investigation Agency spokesperson said Imran was involved in carrying out espionage activities and working for Pakistan's ISI.

The case relates to an international espionage racket in which Pakistan-based spies recruited agents in India for collecting sensitive and classified information regarding locations/movements of Indian naval ships and submarines, and other defence establishments.

Investigation revealed that few navy personnel came in contact with Pakistani agents through social media platforms such as Facebook and WhatsApp, among others.

They shared classified information for which money was deposited into their bank accounts through ISI's Indian associates who had business interests in Pakistan.

A chargesheet was filed in the case on June 15 against 14 accused.

Imran was associated with Pakistani spies/agents under the guise of cross-border cloth trade, the NIA official said.

As per the directions of Pakistan-based spies, he deposited money into the bank accounts of Indian Navy personnel at regular intervals in exchange for sensitive and classified data provided by them, the spokesperson said.

Some digital devices and incriminating documents were seized in a search conducted at his house on Monday, the official said.

Further investigation in the case is underway, he said.