Tunisia's Interior Ministry has released security camera footage of the gunmen walking through the Bardo museum during the attack that killed 21 people.

The one-minute video posted on the ministry's Facebook page Saturday shows the two men walking through the museum, carrying assault rifles and bags.

At one point they encounter another man with a backpack walking down a flight of stairs. They briefly acknowledge each other before they walk on in opposite directions. There was no explanation of who the third man was.

One of the attackers is wearing a baseball cap and a heavy jacket, while the other has a red hoodie and track pants.

The video also shows stills of the dead gunmen, including a picture indicating that at least one was wearing an explosive belt.