A man has been criticised for his "very serious and dangerous stunt", after he filmed himself parachuting from the top of the crane outside Norwich Castle.

In a video posted online, he can be seen perched at the top of the 104ft structure in the middle of the night before throwing himself off.

Around ten seconds later, after his parachute deploys, he lands in the middle of a deserted Castle Meadow, close to the Bell pub.

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Police have said they are investigating the incident, while Norfolk Museum Services - which has responsibility for the castle site - has strongly condemned the man's actions.

A spokesman said: “This was a very serious and dangerous stunt.

"Safety and security at Norfolk museums is of the utmost importance, and we constantly monitor and improve our arrangements.

"We are working with the police to make sure this doesn’t happen again.”

The video - captured on a helmet-mounted camera - was posted on Instagram two weeks ago by a user under the name of a.rchie.

In the post, the parachutist says: "Special one in the city. Waited five months for the right position and conditions."

The crane has been temporarily installed at the site to help with the multi-million pound Palace Reborn project, in which the keep of Norwich castle is being restored to its Norman heyday.

A representative from Morgan Sindall construction, which operates the crane, said it had been alerted to an intruder by the site's CCTV alarm.

The spokesman said: “The site’s CCTV system alerted us to an intrusion at Norwich Castle, which we reported to the police both at the time and then again when we became aware of the dangerous activity undertaken.

“Needless to say, ourselves and the Norfolk Museums Service take safety and security very seriously and follow industry standard protocols.

"This has involved implementing a range of robust security measures across the site which are regularly and diligently reviewed, monitored and maintained.

"Since the incident we have also put in place a number of additional security enhancements."