US and Libyan forces captured Saifallah Benahssine, the leader of Tunisia's Islamist militant group Ansar al-Sharia, in the Libyan city of Misrata on Monday, Tunisia's state news agency TAP said, citing a security source.
The US embassy in Libya and Libyan government officials did not immediately respond to a request for confirmation of the arrest of Benahssine, also known as Abu Iyadh.
But the capture of such as high-ranking Tunisian Islamist militant in Libya would indicate close ties among Islamist groups across North Africa. In October, US forces captured a top Al-Qaeda suspect in a raid in Tripoli.
A former fighter in Afghanistan, Benahssine had declared loyalty to Al-Qaeda and was accused of inciting an attack on the US embassy in Tunisia in September 2012.
Ansar al-Sharia was one of the hardline groups to emerge after the Tunisia's revolt against its autocratic leader three years ago. Militant violence has increased in Tunisia since the government began a crackdown on the group this year.