A group of former researchers at South Korea's state-run arms development agency are under investigation for allegedly leaking military secrets to private firms and institutions, military authorities said Monday.

“We think about 60 workers left the agency with trade secrets. The National Intelligence Service, along with other authorities, are looking into the event,” a military official said, adding that authorities were focusing on some 20 agents suspected of glaring malfeasance.

Authorities were given an anonymous tip last year that retiring senior officers at the agency often took away classified material with them. Some of those under the probe reportedly admitted to leaking sensitive information, calling it a “common practice” that retirees provide secrets to the firms or institutions that hire them.

The information involved the latest artificial intelligence and drone technologies as well as technologies related to cyberwarfare, according to authorities, which have yet to determine how the leak had taken place and the damage done to the agency.

“We certainly take the issue very seriously,” an official at the agency said. “We will come up with a foolproof plan to better protect our technologies here.”

By Choi Si-young (siyoungchoi@heraldcorp.com).