According to the Tunisian authorities, terrorist Seifeddine Rezgui had help in carrying out the attack at Sousse holiday resort.
Mohamed Ali Aoui said Seifeddine Rezgui’s father and three friends he lived with in Kairouan, where he studied, had been detained for questioning.
Holiday companies put on extra flights over the weekend for people wanting to return home. Flights to Tunisia have also been cancelled.
The Tunisian government has brought in increased security measures.
A total of 38 people were killed on June 26 on a beach near Sousse by the gunman with links to Islamic State (ISIS) extremists.