21 March 2015
Last updated at 23:43
The Tunisian government has released footage showing gunmen walking through the Bardo museum during the attack that killed 25 people on Wednesday.
At one point it shows the two attackers bumping into another man who is allowed to flee after the brief encounter.
Authorities said they had arrested more suspects in connection with the attack in the capital, Tunis.
The gunmen are said to have been trained in Libya in an area controlled by Islamic State (IS) militants.
IS has said it was behind the attack on the museum, which is next to the country’s parliament.
The men, named as Yassine Laabidi and Hatem Khachnaoui, were killed in a gunfight with security forces inside the building. At least one of them was wearing an explosives belt.
A service for victims of the attack was held at the Cathedral of St Vincent de Paul in Tunis
The brother of Yassine Laabidi, one of gunmen, said he had been “brainwashed by swines”
The security camera footage, released by the interior ministry, shows the men carrying assault rifles and bags as they walk through the museum.
It also captures the moment a startled visitor comes face to face with the gunmen as he tries to flee the building. The gunmen briefly point their guns at the man but allow him to run away as they make their way up a staircase.
Earlier, a spokeswoman for the prosecutor said substantial progress had been made in the investigation – but she did not give any details.
Authorities have arrested more than 20 suspects since the attack, including 10 people believed to have been directly involved.
“There is a large-scale campaign against the extremists,” interior ministry spokesman Mohamed Ali Aroui told reporters.
Tunisia has seen an upsurge in Islamist extremism since the 2011 revolution that ousted dictator Zine al-Abidine Ben Ali and sparked the Arab Spring.
The brother of Yassine Laabidi, one of the gunmen, said 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”.
There was a heavy police presence in the capital on Sunday. Hundreds of people gathered for a service in the cathedral, lighting candles for the victims.
Twenty foreign tourists were among those killed, including British, Japanese, French, Italian and Colombian visitors were among the victims.