Forces loyal to renegade Libyan general Khalifa Haftar have been accused of burning more than 6,000 books, including works on religion, politics, poetry and philosophy.
According to a video posted on Facebook by Al Manara, a Libyan media platform, more than 6,000 books - including reported biographies of the Prophet Muhammad - were destroyed by a police force in the eastern city of Benghazi on Saturday.
The video showed a police officer claiming that the seized literature was promoting the ideas of "Daesh" (the Arabic term for Islamic State of Iraq and Levant or ISIL), as he sat behind a desk covered with books, including classical Islamic works.
The officer said the books "promoted violence" and the "ideas of the Muslim Brotherhood", which has been banned by UAE and Egypt.
In January, more than 100 Libyan writers and intellectuals, including renowned Brazilian novelist Paulo Coelho, condemned a seizure of books deemed "erotic" or anti-Islamic by authorities in eastern Libya.
Books by Egyptian Nobel Prize-winning novelist Naguib Mahfouz and Arabic translations of books by German philosopher Friedrich Nietzsche were allegedly among dozens seized from a truck heading from Tobruk to Benghazi.
A video of the book seizure was posted online where security officials denounced the "cultural invasion," claiming the works promoted sorcery, as well as erotic materials.
In an open letter, more than 100 novelists denounced the confiscation, calling it "intellectual terrorism".
Libya descended into a civil war after a popular uprising toppled long-time leader Muammar Gaddafi in 2011.
The country has splintered into rival political and armed groups, with the factions backing opposing governments and parliaments in the east and the west.
Haftar, who has the backing of Egypt and the UAE, controls large parts of eastern Libya and is aligned with the Tokruk-based government. He has staged several bloody attacks against other Libyan militias and designated the Muslim Brotherhood as a "terrorist group".