Tunisian officials have signed over to their Algerian counterparts an ancient Roman artefact that was stolen during Algeria’s civil war almost 20 years ago.

The Tunisian and Algerian ministers of culture met on Sunday in the ruins of the ancient city of Carthage, near the capital Tunis, to sign a formal agreement to repatriate the Gorgon Mask.

Algerian Minister of Culture Khalida Toumi said returning the artefact was important for the bilateral relationship between Tunisia and Algeria.

This special regional situation requires the reinforcement of the brotherhood bonds that connect us. - Khalida Toumi, Algerian Minister of Culture

"This special regional situation requires the reinforcement of the brotherhood bonds that connect us," she said during the ceremony, calling the artefact part of Algeria’s "national and cultural identity".

The one-metre-tall and more than 300kg mask was stolen in 1996. It was found in 2011 in the house of Sakher al-Materi, the son-in-law of former Tunisian President Zine El Abidine Ben Ali.

The details of how the mask was stolen and taken to Tunisia are still unclear. According to Tunisian Minister of Culture Mohammad Sakli, the discovery of the artefact, which depicts a Greek mythological creature, was made when a video of al-Materi’s looted home was aired on Tunisian television shortly after the country's 2011 revolution.

"Experts and scientists called [to] the attention of the Tunisian judiciary that this piece might actually belong to Algeria," Sakli told Al Jazeera.

Three years passed between the artefact's discovery and its return because of a slow judicial process in Tunisia, Sakli said, adding the government could not force the judiciary to expedite the case.

Toumi referred to the theft, which happened in the midst of Algeria's civil war, as a "stab in the back in a time when the Algerian people and its institutions were occupied [with] saving Algeria as a state, nation, and society". She announced that a joint Algerian-Tunisian committee of experts would be formed to examine cases of illegal trafficking of cultural artefacts.

In Tunisia, home to ancient Phoenician, Roman, and Arab civilisations, many archaeological artefacts found their way into the hands of the Ben Ali family.

Last December, Tunisian national television reported that nine people had been arrested for selling ancient coins, jewelry, and stone jars that had been stolen from al-Materi’s villa during the looting that followed the 2011 revolution.