The artefacts, pulled just days before the sale in London on April 15, are thought to have links to art dealers Giacomo Medici and Gianfranco Becchina, both convicted in the last decade of trafficking millions of pounds worth of antiquities.
The withdrawn lots had all appeared at auction before: a small Etruscan terracotta antefix, c.6th-5th century BC (estimate £3000-5000), and a c.350-330 BC Apulian red-figured hydria (estimate £12,000-18,000) had both sold at Sotheby's London in the 1980s, while an Attic black-figured amphora from c.540-520BC estimated at £50,000-70,000 had sold at Christie's New York in 2002, passing through various owners including antiquities dealers Charles Ede in 2006.
The fourth item, a Roman gold boss bracelet dated c.1st century BC (£12,000-18,000 estimate), had been sold by Christie's on two previous occasions, in 2003 and 2007.
Seized Archive
Dr Christos Tsirogiannis, a research assistant at the University of Glasgow, is said to have uncovered images of the withdrawn lots in archives seized from the two art dealers and accused Christie's of failing to carry out "due diligence".
In April 2014, Dr Tsirogiannis also raised the alarm, through a leading news story in The Times, over two lots due to be sold in London at Bonhams and Christie's which were reportedly listed in the Medici archive. Both auction houses withdrew the lots immediately once they became aware of the allegations.
While academics are permitted access to the archives, auction houses and other trade professionals are denied it - primarily because of confidentiality regarding its use as evidence in a criminal investigation. This has long been an area of dispute, with many in the trade questioning why the Medici archives are not made available at least to more law enforcement agencies as well as stolen art registers.
A Christie's spokesperson said of the withdrawn artefacts: "We will now work with Scotland Yard's Art and Antiques Unit to discover whether or not there is a basis for concerns expressed over the provenance."
Christie's have called for the archives to become freely available.
