Tunisia's Interior Ministry has released surveillance footage showing the two gunmen who killed dozens of people, during an attack on inside Tunis' Bardo Museum Wednesday.

The footage shows men armed with what appear to be assault rifles walking through the museum, at one point bumping into a member of the public, who they allow to leave after their unexpected encounter.

Authorities in Tunisia have arrested more than 20 suspected militants, in a crackdown launched after the attack, which killed mostly foreign tourists. Ten of those arrested are believed to have been directly involved in the attack, Reuters reported.

Among those taken into custody are believed to be four relatives of Hatem Khachnaoui, one of the assailants, who was slain by police. Two of Khachnaoui's brothers, his sister and father were reportedly arrested Wednesday near the border with Algeria.

Tunisian authorities claimed that the two attackers, Khachnaoui and Yassine Laabidi, had trained in camps in Libya in an area controlled by the Islamic State group, Sky News reported.

On Saturday, Laabidi's brother told the BBC that his family were struggling to understand what had happened.

He described Laabidi as a sociable person who "enjoyed a drink with mates" but said he had been "brainwashed by swines who send young men to their death in the name of religion".

Museum patrons who witnessed the carnage wrought by the attackers however, told a different story. Josep Lluis Cusido, the mayor of the small Spanish town of Vallmoll, told the Associated Press: “They looked to see how they could inflict the most damage possible. I saw one group who was in the museum who took refuge in a room. ... They went in there and machine gunned them all."

The unedited video of the incident, posted on the Facebook page of Tunisia's Interior Ministry, shows stills of the dead gunmen, including a picture indicating that at least one was wearing an explosive belt, the Telegraph reported.