Noureddine al-Naibi was arrested on Sunday at the Ras Jedir border post on suspicion of indirect involvement in the attack, ministry spokesman Mohamed Ali Aroui told AFP.

He said the suspect was using a forged passport.

Last week, a young Moroccan man was arrested in Italy for allegedly helping in the March 18 attack carried out by two Tunisians who gunned down 21 tourists and a policeman before they were killed.

Abdelmajid Touil, 22, a migrant smuggled into Italy by boat in February, has insisted on his innocence and is fighting a Tunisian request for his extradition.

Around 50 people have been detained in Tunisia as part of an investigation into the attack claimed by the Islamic State of Iraq and Syria (ISIS).

Tunis pinned responsibility for the museum massacre on Lokmane Abu Sakhr, an Algerian militant killed by Tunisian security forces at the end of March.

Tunisia has also issued an arrest warrant for an Algerian national following the museum attack.