The men, aged 24, 41, 44 and 56 were among 19 people snatched by police in dawn raids across the UK and were being held on suspicion of conspiracy to burgle. Hundreds of officers from 26 police forces and the Serious Organised Crime Agency (SOCA) are involved in the operation and searches are ongoing at various locations. The investigation is in connection with six crimes over a four-month period at museums and auction houses across England. Chinese artefacts and rhinoceros horn were stolen in five incidents - three at Durham Museum, Gorringes Auction House in East Sussex and the Fitzwilliam Museum in Cambridge. While much of the property was subsequently recovered, several high-value items are still missing.Others arrested include five men and two women from London, two men from Essex, three men from Norther Ireland as well as men from Sussex, the West Midlands and Nottingham. Chief constable Mick Creedon, lead for serious organised crime for the Association of Chief Police Officers, said: The series of burglaries last year had a profound effect on museums and similar institutions and we are committed to bringing all those who were involved in the conspiracy to justice. Many of the stolen Chinese artefacts are still outstanding and a substantial reward remains on offer for information which leads to the safe return of those priceless items. Anyone with any information should call Crimestoppers, anonymously, on 0800 555111.