WASHINGTON – Testifying out of sight, ex-CIA Director David Petraeus told Congress Friday that classified intelligence showed the deadly raid on the U.S. Consulate in Libya was a terrorist attack but the administration withheld the suspected role of al-Qaida affiliates to avoid tipping them off.

The recently resigned spy chief explained that references to terrorist groups suspected of carrying out the violence were removed from the public explanation of what caused the attack so as not to alert them that U.S. intelligence was on their trail, according to lawmakers who attended Petraeus' private briefings.

He also said it initially was unclear whether the militants had infiltrated a demonstration to cover their attack.