The 163kg of cocaine, with a street value of £11.5m, was found on Sunday at a house in Ostend, Belgium, and was thought to have been on the way to Britain.

Six British people, five men and a woman, were arrested at London's Heathrow airport and during six raids in south-east England on Sunday night. A Belgian man was arrested in Ostend.

Raids were carried out at Wendover, Buckinghamshire; Runwell, Wickford and Clay Hill, Essex as well as Bushey and Watford, Hertfordshire.

Two further arrests were made on Monday at Runwell where cannabis plants and cocaine were seized.

On Monday afternoon, two men were arrested at Newcastle Airport. One had just flown in from Europe.

The 10 British people are being held at police stations in the South East.

Police believe the two-year Operation Pierrot, organised by the squad and its predecessor, the South East Regional Crime Squad, has broken up one of the UK's major drug gangs.

The operation also included the National Criminal Intelligence Service, Customs and Excise and the Belgian Gendarmerie, which seized the drugs on behalf of the NCIS.

Detective Chief Inspector Peter Spindler, of the NCIS, said: "The success results from the work of our own highly professional staff, and from close co-operation with law enforcement colleagues in this country and in Europe."