An international mystery concerning the alleged theft of priceless ancient papyrus biblical fragments from a collection held at Oxford University has led to the arrest of a classics professor on suspicion of theft and fraud.

Dr Dirk Obbink, an associate professor in papyrology and Greek literature at the university, was detained by officers from Thames Valley police.

The force had received a report claiming the papyrus fragments that had been housed at the renowned Sackler Library in Oxford, which ended up in a biblical museum in the US, had been stolen.

Officers said the alleged theft was reported to them on 12 November. They made the arrest last month and the person detained has been released while inquiries continue.

Obbink, 63, has denied any wrongdoing, and has said the claims are a “malicious attempt” to harm his reputation and damage his career.

It is alleged that materials held at the Sackler Library had ended up in the US, in a collection belonging to the Museum of the Bible in Washington DC. It was founded in 2017 by the Green family, billionaire American evangelical Christians who own Hobby Lobby, a chain of crafting stores.

Obbink was suspended from duties at Oxford in October 2019 after an investigation into the disappearance of ancient papyrus fragments from the Oxyrhynchus collection, cared for in the Sackler Library and owned by the Egypt Exploration Society (EES).

The EES says the materials were removed from Oxford University premises and allegedly sold to the Museum of the Bible.

Dr Carl Graves, the EES director, said the society had given statements to the police investigation about what had gone missing. He said the Museum of the Bible had been cooperative and the missing fragments – 13 in total – had been returned.

Graves said: “These are early fragments of the gospels or biblical fragments. They are testament to Egypt’s early Christian heritage and are early evidence of biblical scripture. We don’t value them monetarily but they are priceless and irreplaceable.”

Some of the fragments in the collection contain only one or two words, while others are larger, and Graves said it had taken decades of work to piece them together. The fragments come from Genesis, Exodus and Deuteronomy, among others.

In a statement, Obbink previously told the Guardian he denied any wrongdoing. “The allegations made against me that I have stolen, removed or sold items owned by the Egypt Exploration Society collection at the University of Oxford are entirely false,” he said.

“I would never betray the trust of my colleagues and the values which I have sought to protect and uphold throughout my academic career in the way that has been alleged. I am aware that there are documents being used against me which I believe have been fabricated in a malicious attempt to harm my reputation and career.”

The Guardian has previously reported that Obbink was involved in two businesses, the Castle Folio and Oxford Ancient, which operated in an office located above a branch of TK Maxx in the city.

The arrest was first reported by the Oxford Blue, a student paper.