A Hemel man has been arrested as part of a Europe-wide operation by police in three countries.
Paul Popeanu, 34, of Rossgate, has been charged with conspiracy to burgle and remove criminal property from the UK.
Another man, from Harrow, was charged with the same offence, while three more people were arrested in the UK and six in Romania.
Popeanu has been remanded to appear in custody at Kingston Crown Court on Tuesday, July 23.
The operation was carried out by the Metropolitan Police in conjunction with Romanian National Police and Italian Carabinieri, supported by Europol and Eurojust.
A Joint Investigation Team (JIT) was set up in 2017 between the cooperating countries with the assistance of Eurojust to coordinate the investigation into the theft of 260 priceless antique books.
A total of 45 warrants were executed, including 13 in the UK, on June 15 as part of an international day of action.