The extremist group Ansar al-Sharia has declared Benghazi an "Islamic Emirate" after claiming total control of Libya's second largest city.

"Benghazi has now become an Islamic emirate," official spokesperson Mohammed al-Zahawi of the group told Radio Tawhid.

The al-Qaeda-linked radicals who rose to prominence during the uprising that overthrew dictator Muammar Gaddafi, was blamed for the attack on the US consulate in 2012.

The trend of proclaiming Islamic caliphates or emirates has gathered pace following the recent declaration of an Islamic State in Iraq spanning a region up to Syria by the Islamic State of Iraq and the Levant (Isis).

The Yemeni-based Al-Qaeda of the Arabian Peninsula (AQAP), the most powerful arm of al-Qaeda, has also expressed its intentions to declare eastern Yemen an emirate.

The latest announcement by the Ansar al-Sharia fighters in Libya has been dismissed by pro-government forces.

"The national Libyan army is in control of Benghazi and only withdrew from certain positions for tactical reasons. The claim that Benghazi is under the control of militias is a lie," Khalifa Haftar, a former army general who is aware of the latest developments, told Al Arabiya channel.

The emirate declaration comes a day after the Libyan militants comprising former rebels and Islamist fighters captured the army base in Benghazi killing dozens.

The police have so far found 78 bodies, mostly of soldiers, in Benghazi following the two-day fighting.