The source said al-Qaida leader Ayman al-Zawahiri dispatched a veteran fighter to Libya in May to recruit fighters in the region near the Egyptian border.
He is believed to have mobilized some 200 people to join al-Qaida's efforts, CNN said Friday.
Western intelligence agencies have been concerned for some time about the potential for Islamist extremists to gain a foothold in Libya after the fall of former leader Moammar Gadhafi. CNN said militant groups have long been present in eastern Libya, although they were suppressed by Gadhafi's regime.
Notable deaths of 2014 [PHOTOS]