Oxford University is probing claims that one of its academics sold ancient fragments of Bible from a charity's archive to a US company.
Classics professor Dirk Obbink has been accused by the Egypt Exploration Society (EES) of selling 11 pieces from its Oxyrhynchus Collection.
The items - held at the university's Sackler Library - ended up at the Museum of the Bible in Washington DC.
Prof Obbink, who has been contacted for comment, remains at the university.
The ancient Greek texts written on fragments of papyrus were originally found during the early 20th Century in the Egyptian city of Oxyrhynchus.
In a statement on its website, the EES says the museum has told it that the fragments were sold by the lecturer in papyrology.
The charity said: "The MOTB [Museum of the Bible] has informed the EES that 11 of these pieces came into its care after being sold to Hobby Lobby stores by Prof Obbink, most of them in two batches in 2010."
It added it had not reappointed the professor as general editor of the collection in 2016 because of "concerns which he did not allay" over his alleged involvement in the marketing of ancient texts.
The EES said it also banned him from access to the collection in June this year "pending clarification", after a 2013 contract reportedly for the sale of four texts from him to Hobby Lobby Stores - an arts and crafts company - was made public by an academic at an Australian university.
The MOTB has agreed to arrange for 13 pieces to be returned to the EES.
In a statement, the museum said Hobby Lobby had acquired the items in good faith between 2010 and 2013 from a "known expert from Oxford University", and that it would continue to assist the EES in "recovering other items that may have removed".
Hobby Lobby declined to comment.
In 2017 Hobby Lobby was forced to forfeit thousands of smuggled artefacts it had bought for the MOTB. The company said at the time it "did not fully appreciate the complexities of the acquisitions process" and that it had relied on dealers' expertise.
Hobby Lobby's president Steve Green also serves as the chairman of the museum, which opened in 2017, and was behind its founding.
An Oxford University spokesman said: "We can confirm we are engaging with the Egypt Exploration Society with regard to the allegations concerning papyri from the Oxyrhynchus Collection.
"The university is conducting its own internal investigation to seek to establish the facts."