The valuable artifacts stolen from the British Museum in London are believed to be around 2,000, with an estimated total value reaching into the millions of pounds, according to reports.

Last week, the British Museum announced that items from its collection were found to be "missing, stolen or damaged" and an unnamed member of staff has been sacked.

Legal action is being taken by the museum against the individual, and police are investigating but no arrests have been made.

The museum has not specified how many items have been stolen or detailed what the missing items are, saying only that were "small pieces" including "gold jewelry and gems of semi-precious stones and glass dating from the 15th century B.C. to the 19th century A.D."

The number of the stolen items is now believed to be "well over 1,000″ and "closer to 2,000," with a value running into "millions of pounds," the Daily Telegraph reported.

The artifacts have not recently been on public display and were kept in a storeroom, mainly used for research and academic work, the museum previously said.

It appears "increasingly likely" that the museum might never know exactly what has been stolen because of "gaps in its inventory," the paper said.

An independent review of security has been launched and the matter is also under investigation by the economic crime command of the Metropolitan Police.

A museum source told the Telegraph that the directorate’s handling of the case has been "negligent and incompetent" and that evidence presented to them was ignored.

An antiquities expert reportedly told the museum three years ago that items from its collection were being offered for sale on eBay, with one Roman object, valued at 25,000 pounds to 50,000 pounds ($32,000-$64,000) by dealers, offered for just 40 pounds.

The independent review will be led by former museum trustee Sir Nigel Boardman, and Lucy D’Orsi, chief constable of the British Transport Police, who will "kickstart" a "vigorous" program to recover the stolen items.

The British Museum declined to comment while the police investigation is underway.