Facebook announced on Thursday that it had identified and blocked a group of hackers operating from Iran that had attacked Defense Ministry officials in the United States and Europe.

A group of hackers known as "Tortoiseshell" used Facebook to gather information about the targets before planting malware on their computers to spy on them.

The group mainly attacked military and defense and space companies in the United States and to a lesser extent in the UK and Europe.

"It's hard to know how successful the campaign was, but it had all the hallmarks of a well-funded operation," said Mike Deblianski, Facebook's chief cyber espionage investigator.

Facebook explained that its network was one of the components of the extensive electronic espionage operation, which included a number of platforms.

The social network has been used, through various tactics such as creating fake accounts, contacting targets and building trust so that they click on malicious links.

The hackers pretended to recruit workers for a security company as well as tried to recruit journalists or hotel workers.

The group has created domain names and sites that impersonate official sites, such as the U.S. Job Search Site.

The hackers also used "their own" malware developed by them, which Facebook believes found to have indirect links to the Iranian Revolutionary Guards (IRGC).