Photographs seized by police suggested that the sculptures – funerary busts and a marble statue of a youth from the second century AD – were illicitly excavated, archaeologists told the Guardian.
A spokesman for Bonhams auctioneers said: “Whenever a serious question is raised about an item’s provenance we withdraw it from sale pending an internal investigation. We take rigorous care to ensure that we only sell items that have a clear provenance.”
Dr David Gill, reader in Mediterranean archaeology at Swansea University, said that the four antiquities bore soil traces that indicated they were excavated during illegal digs. Images in the Bonhams auction catalogue show the same sculptures cleaned and restored.
Archaeologists remain concerned about illegal trading of antiquities and some believe insufficient checks are carried out into their provenance.
Lord Renfrew, the eminent Cambridge archaeologist, warned that “such sales are maintaining London’s reputation as a clearing house for looted antiquities”.
Gill said the withdrawal was the latest in a series of such incidents in London.