Police arrested around 40 people yesterday in dawn raids on gangmasters suspected of employing illegal immigrants. It is thought the raids may have broken up one of the most ruthless gangmaster operations in the country.

Ten men and 28 women were held in Grampian in Scotland and two men were held in Norfolk. The ring is alleged to have brought people from eastern European countries to work in Britain, supplying them with fake work permits and hiring them out as cheap labour to fish processing companies in Scotland.

The raids – codenamed Operation Absent – involved officers from the Norfolk, Grampian, Cambridgeshire and Metropolitan Police and representatives from the Immigration Service.

A private member’s bill to license gangmasters won wide support from MPs after 20 Chinese cockle-pickers died in Morecambe in February, but ministers now fear the bill will not be given sufficient parliamentary time to clear.