The museum says the pieces include "gold jewellery and gems of semi-precious stones and glass dating from the 15th Century BC to the 19th Century AD".
The British Museum has dismissed a member of its staff after items dating back as far as the 15th century B.C. were found to be missing, stolen or damaged.
The museum said it has also ordered an independent review of security and a ‘‘vigorous program to recover the missing items.″
The stolen artefacts include gold jewellery and gems of semi-precious stones and glass dating from the 15th century B.C. to the 19th century A.D. Most were small items kept in a storeroom and none had been on display recently, the museum said.
British Museum director Hartwig Fischer apologized and said the museum would "throw our efforts into the recovery of objects".
"This is a highly unusual incident. I know I speak for all colleagues when I say that we take the safeguarding of all the items in our care extremely seriously,” he added.
"We have already tightened our security arrangements and we are working alongside outside experts to complete a definitive account of what is missing, damaged and stolen."
Former chancellor George Osborne, who chairs the British Museum, stated that the priority was threefold: “First, to recover the stolen items; second, to find out what, if anything, could have been done to stop this; and third, to do whatever it takes, with investment in security and collection records, to make sure this doesn’t happen again.”
The museum said legal action would be taken against the dismissed staff member and that the matter was under investigation by London’s Metropolitan Police Service.
The 264-year-old British Museum is a major London tourist attraction, drawing visitors from around the world who come to see a vast collection of artefacts ranging from the Rosetta Stone that unlocked the language of ancient Egypt to scrolls bearing 12th century Chinese poetry and masks created by the indigenous people of Canada.
But the museum has also attracted controversy because it has resisted calls from communities around the world to return items of historical significance that were acquired during the era of the British Empire. The most famous of these disputes include marble carvings from the Parthenon in Greece and the Benin bronzes from west Africa.