Microsoft on Friday said that hackers linked to the Iranian government had targeted a U.S. presidential campaign, government officials, media and prominent expatriate Iranians.

The tech company did not however reveal the details of the campaign, citing privacy concerns.

Corporate vice president for security Tom Burt said in a blog post that owners of four accounts that were successfully breached had been notified.

He added that the accounts that had been compromised were not related to U.S. campaigns or officials.

Burt said the attacks by a group Microsoft calls Phosphorous occurred during a 30-day period in August and September.