An expert in recovering stolen works of art has questioned the safety of the disputed Parthenon Marbles held at the British Museum after the alarm was raised over missing artefacts.

The London institution announced on Wednesday it is taking legal action against an unnamed staff member, who has been dismissed, and launched an independent security review after items were found to be missing, stolen or damaged earlier this year.

The Metropolitan Police say they are investigating. The staff member has not been arrested.

The musuem says the items include gold jewellery, semi-precious stones, and glass dating from the 15th Century BC to the 19th Century CE, which were not recently on public display and were mainly used for research and academic work.

Christopher Marinello, a lawyer and expert in recovering stolen art, told the PA news agency that itemising the stolen objects “could take weeks, if not months”.

He said the debacle calls into question Britain's stance in the the long-running dispute over the fate of the Elgin Marbles.

Greece has campaigned for decades for the return of the Parthenon Sculptures, which once decorated the Acropolis in Athens.

The country has long claimed they were illegally acquired during foreign occupation, and has a place ready in its own museum.

Mr Marinello said: “It makes one wonder whether the Parthenon Marbles are safe in the British Museum after all, and perhaps they should be returned to the museum in Athens for their security.

“One of the arguments the British Museum has always given is they’re better preserved in the British Museum than they are in Athens.

“(They said they’re a) secure facility, and maybe that’s not entirely true.”

British Museum director Hartwig Fischer said it had “tightened” its security arrangements following the theft, while chairman George Osborne said its priority is to recover the stolen items, find out if is anything could have been done to stop it, and do whatever possible to prevent it happening again.

Mr Marinello, an expert in recovering looted and missing works of art including restitution cases for foreign governments and heirs of Holocaust victims, told PA: “Let’s face it, we hate to see museums say ‘we’re going to tighten security’ after a theft, why wasn’t security tightened before? It’s not enough to have cameras on the walls, one needs to properly vet their employees.

“There needs to be sign-ins and sign-outs for every object that’s being studied.

“There are plenty of things that museums need to do and if any museum knows how to do it, it’s the British Museum.”

The specialist also questioned why “one of the most well-funded museums in the world” is having problems with theft, adding it is “too early to know the extent of the damage”.

He said it is now “critical” that the museum can decipher a comprehensive list of what has been lost.

“I believe that until they do a proper inventory and compare with previous inventories, they won’t know what is still missing,” he said.

“It’s imperative that they publish a list of everything that might be missing so that it can be recovered.

“It could take weeks, if not months.”

Mr Marinello, who founded Art Recovery International in 2013, concluded: “It’s unfortunate that we entrust these institutions to preserve our cultural heritage, yet we don’t give them the proper funding for them to do so.”

The British Museum previously said it will be taking legal action against the unnamed staff member, while the matter is also under investigation by the economic crime command of the Metropolitan Police.

A spokesperson for the Met said: “We have been working alongside the British Museum.

“There is currently an ongoing investigation – there is no arrest and inquiries continue. We will not be providing any further information at this time.”

Reporting by PA