The British Museum has begun recovering some items that were taken from the prestigious institution and sold online, museum chair George Osborne said on Saturday.

Osborne's comments follow revelations that the museum failed to properly heed warnings that items purportedly from its collection had been appearing for sale online.

The extent of the theft was previously unclear. The museum had previously said that the majority of the missing items were "small pieces kept in a storeroom" of one collection. They include gold jewelry, gems of semi-precious stones and glass dating from the 15th century BC to the 19th century AD. None of the items had recently been on public display.

Osborne, the former UK Chancellor of the Exchequer, told BBC Radio 4's "Today" program on Saturday that about 2,000 artifacts went missing, some of which have already been recovered.

"We're dealing with lots of honest people who will return stolen items, others may not," Osborne said.

The scandal appears to date back to 2021, when a Danish art dealer got in touch with the British Museum to say he had spotted several items he believed to be from the museum's collection for a sale online. The British Museum initially claimed to have carried out a thorough investigation, but a follow up probe found the first response to be insufficient, Osborne said.

"We obviously have to improve security," Osborne said.

The British Museum, founded in 1753, is one of the world's most well-known and prestigious museums. Its display impressive historic artifacts like the Rosetta Stone and the Parthenon Sculptures regularly draws visitors from across the globe.

The scandal has proved deeply embarrassing for the museum, given both its stature and the repeated calls for the institution to return many of its artifacts that were themselves stolen under the British Empire.

Museum director Hartwig Fischer stepped down on Friday and an unidentified employee was fired on Wednesday.

"Yes, the museum has made mistakes. Yes, we've apologized for them. But we're cleaning up the mess and we're going to be that British museum that I think the nation and the world can be proud of," he said.

Osborne said he hoped the police inquiry underway may shed light on how "the museum missed some of the signals that could have been picked up."

Osborne acknowledged that although the "obvious thing" would be for the museum to publish a list of the stolen items, there are fears that not everyone would respond to the list "in the best possible way." He also said it falls within the remit of law enforcement to publish such a list.

One key challenge in the recovery efforts has been that not all items in the museum are cataloged. Osborne said following the incident, staff are accelerating its effort to catalog all the items in its collection.

"The truth is we didn't have a complete catalog of everything, and you know, obviously, I've got to be careful what I say because there is a police investigation but someone with knowledge of what's not registered has a big advantage in removing some of those items," Osborne said.