Immigration officials discovered some of the drugs hidden in souvenirs from South Africa at Heathrow, sparking an investigation that netted 360 kilograms of heroin in total, the UK Border Agency said.

Seven people have been arrested in both countries over the total seizure, worth $41-million dollars, the agency said.

Thousands of kilogrammes of cannabis were also discovered, the agency said.

"This latest detection of heroin at Heathrow, believed to be our biggest ever, highlights our success in preventing class A drugs entering the UK," said Philip Astle, the UK Border Agency's Heathrow director.

About 165-kilograms were discovered at Heathrow, a record seizure for the world's busiest airport, on September 9 in the consignment of souvenirs.

After an investigation, police seized another 80 kilograms and arrested two people in Kent, southeast England, charging one with conspiracy to import drugs and possession, the agency said.

Acting on information from Britain, South African police arrested five people, including three British nationals, and seized 115kgs of heroin and 6500 kgs of cannabis in a warehouse outside Durban.

Eyewitness News reports that the Hawks are investigating several local companies, including Durban-based SA Cultural Curios in connection with the bust.

The Hawks' Devon Naiker said six people were arrested ? one of them is the director of SA Cultural Curios Gopal Ghanesh.

"These seizures are a great example of what can happen when partners work together, said Britain's Serious Organised Crime Agency deputy director Andy Sellers.

"Both ends of this international chain have been attacked, and a significant amount of heroin and cannabis has been kept off the UK's streets."