A member of staff at the British Museum has been sacked after jewellery and gems from its collection were found to be “missing, stolen or damaged”.

In a statement, the museum said the items included “gold jewellery and gems of semi-precious stones and glass dating from the 15th Century BC to the 19th Century AD”.

The majority were “small pieces kept in a storeroom belonging to one of the museum’s collections”, officials said.

They were kept primarily for academic and research purposes and none had recently been on public display.

The museum will be “taking legal action against the individual” and the Metropolitan Police’s economic and crime command is investigating, the museum said.

“This is a highly unusual incident,” said director Hartwig Fischer.

Security has already been tightened, he added, and the museum is “working alongside outside experts to complete a definitive account of what is missing, damaged and stolen”.