By james art 
Part of the museum’s permanent collection was closed on Friday, while temporary exhibitions will remain closed over the weekend following the alleged attack.
The museum said the former member of staff, who had recently been fired, had “transferred” to the site and was arrested at the scene.
A spokesman said on Saturday: “An IT contractor who was made redundant last week broke into the museum and shut down several of our systems. Police attended and he was arrested at the scene.
“We are working hard to get the museum back to full operation but unfortunately our temporary exhibitions were closed today and will remain so over the weekend – ticket holders have been notified and refunds are being processed.”
The incident comes after around 1,500 objects were discovered missing or stolen from the museum’s collection in August 2023.
Legal proceedings were launched last year against the former curator, Dr Peter Higgs, who was sacked in July 2023. after a more than 30-year career in the Department of Greece and Rome.
Since then, hundreds of treasures have been returned, including from collectors around the world.
Last year, the body had a temporary exhibition where it displayed recovered artefacts, including ancient gems.
After the furor, the museum’s director Hartwig Fischer resigned and after an interim head was appointed, Nicholas Cullinan, who had previously been in charge of the National Portrait Gallery, took over the role.
The Metropolitan Police have been contacted for comment.