The explosion took place just before Friday prayers at the Saad Ibn Ibada mosque located between Benghazi's al-Majouri and Berka districts, said Motaz Agouri, an official from Benghazi security directorate's media office. He also said that the two bombs were planted in separate rooms at the site of the mosque.
No group immediately claimed responsibility for the attack.
Photos of the mosque after the explosion emerged on social media sites showing the damaged building with smashed doors and windows, and blood staining parts of the floor.
Later, the United Nations Support Mission in Libya condemned the attack in a statement. "This heinous act should not provide a justification for revenge attacks. Prompt, impartial investigations should bring perpetrators to justice," the group said.
Benghazi, a troubled city with occasional bombings and attacks, has seen often seen fighting between forces loyal to the self-styled Libyan National Army, led by military strongman Khalifa Hifter, and Islamist militia opponents.
In January, a twin car bombing near a mosque in Benghazi's Salmani neighborhood killed at least 33 people.
Libya descended into chaos after the 2011 uprising that toppled and killed ruler Moammar Gadhafi. The country has been since split between rival governments in the east and the west, each backed by an array of militias.
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