An art dealer alerted the British Museum to alleged stolen items from the institution in 2021 but was told "all objects were accounted for".
Ittai Gradel alleged in February 2021 he had seen items online belonging to the museum, according to correspondence seen by BBC News between Mr Gradel and the museum.
Deputy director Jonathan Williams responded in July 2021 to Mr Gradel, saying "there was no suggestion of any wrongdoing".
The British Museum has been contacted for comment.
Williams added during the correspondence that there had been a "thorough investigation" and that the "collection was protected."
The London institution announced last week that it had sacked a member of staff after treasures were reported "missing, stolen or damaged".
Police are now investigating. A statement issued by the Metropolitan police said: "We have been working alongside the British Museum.
"There is currently an ongoing investigation - there is no arrest and enquiries continue. We will not be providing any further information at this time."
The BBC understands that while there are unanswered questions for the museum, due to police involvement, they don't intend to comment further at present.
https://www.bbc.co.uk/news/entertainment-arts-66582935