Nine-pound 19th-century bronze cannon stolen from Royal Armouries collection

Police were called after a nine-pound bronze gun, which is 64.5 inches (1.64 metres) in length and dated to 1859, was taken from a remote location in February, the institution said. Such artillery pieces are named for the weight of the cannonball they fired, and the stolen object would be considerably heavier.

The theft, which did not take place at any of the body's museum venues, was revealed on Thursday as part of a freedom of information (FOI) request by the PA news agency.

It is believed that the incident was a metal theft, meaning the cannon was thought to have been taken for its scrap value, rather than stolen as a "collection object" according to Royal Armouries.

The body, which houses the national collection of arms and armours at the Tower of London, the Royal Armouries Museum in Leeds and Fort Nelson near Portsmouth, also disclosed that other items are missing.

Royal Armouries said that a pair of mounted sword bayonets, worth £500, disappeared while on loan and police officers were called.

As a result of an investigation, other parts of the body's collection were recalled, the institution said.

The cannon, described as a "smoothbore cannon barrel made of bronze", was "removed by thieves from a remote location, offsite from any of the Royal Armouries' venues", according to the institution.

It added: "No monetary valuation was specified for this object. This incident was considered metal theft rather than the object being stolen for its value as a collection object.

"The Royal Armouries staff acted swiftly to escalate the incident to the Executive Board and Board of Trustees in line with our policies. The police were notified and involved, and the Royal Armouries took immediate action to investigate the incident taking remedial action, as necessary."

The bayonets, dated to 1837, were discovered missing by the Royal Armouries in May last year as part of a routine audit.

The museum said: "A full investigation was carried out and the police were informed, but the items could not be located. As a result, other items on loan on display at the same location were deinstalled and are now back at the museum."

The Royal Armouries has not said where any of the items were housed. The institution has a more than 700-year-old history at the Tower of London and "one of the largest collections of historic arms and armour in the world".

Originally a manufacturer of weapons, it has had visitors since 1498 and later became part of the Government before becoming a public body in 1983.

Royal Armouries issued a statement after being asked by PA why the theft was not disclosed, for more information about the locations that the items went missing and for more detail on why all items out on loan were recalled.

The body said: "The Royal Armouries followed all process and procedures relating to the thefts, including disclosing the information to all relevant external parties. In relation to the canon which involved metal theft, there was a risk that publicising this more widely could precipitate an increase in further incidents. There were no staff members involved in either incident."

Police forces have been contacted for comment.

The theft follows the British Museum revealing in August that an unnamed member of staff was sacked and more than 2,000 items - including gold jewellery, semi-precious stones and glass - have been stolen, missing or damaged. Around 350 of the artefacts have since been recovered, the London museum said in October as an investigation by the Metropolitan Police continues.