( CNN ) -- The leader of a Tunisian militant Islamist group was arrested in Libya on Monday , state media reported , citing a security source . Libyan and American forces captured the militant leader , Tunisie Agence Presse reported . But the United States denied any involvement in the reported arrest of Seifallah Ben Hussein Mokni , who is also known as Abu Iyadh and heads Ansar al Sharia in Tunisia . `` Contrary to media reports , U.S. forces were not involved in any operations involving Ansar al Sharia leader Abu Iyadh today in Libya , '' Pentagon spokesman Rear Adm. John F. Kirby told CNN . The Tunisian state media report accused Ansar al Sharia in Tunisia of ties to political assassinations in the country . Ansar al Sharia in Tunisia denied through its official Twitter account that its leader had been arrested in Libya . The statement said that the `` lying media '' reported the `` false rumors '' to `` play a dirty game '' and influence its members to respond physically . Ansar al Sharia in Libya , another Islamist militia group , was believed to be involved in the 2012 U.S. Consulate attack that killed four Americans in Benghazi , Libya .
Tunisian state media says Libyan and American forces captured Abu Iyadh . A Libyan spokesman said American forces were not involved . Ansar al Sharia in Tunisia denies the Islamist group leader 's arrest .