Around 2,000 artefacts including gold jewellery and gems had been stolen from the British Museum over a long period of time, but recovery efforts were already under way, the museum’s chair George Osborne said on Saturday.

The museum, one of London’s most popular attractions whose treasures include the Rosetta Stone, an ancient Egyptian relic inscribed with hieroglyphs and other texts, said last week a member of staff had been dismissed after items dating from the 15th century BC to the 19th century AD had been taken from a storeroom.

Museum director Hartwig Fischer said on Friday he would step down after admitting to failings in its investigation into the theft of items from its collection.