Seven men, including a suspected Hong Kong triad boss, are facing the death penalty on the mainland, accused of being part of a drug cartel flooding Africa with drugs. The men were caught with tonnes of methaqualone, the key ingredient in the manufacture of Mandrax, in police raids on a warehouse in Huangpu in February. Mandrax is usually smoked in a pipe with marijuana. Their arrest sparked recent raids by South African police which netted tonnes of the drug on its way into the country via Durban harbour. Under a joint taskforce including officers from the Hong Kong Police Narcotics Bureau, Guangdong provincial Public Security Bureau and South African security forces, authorities seized three multi-tonne shipments in a month in South Africa's busiest port. In the last port raid, police impounded 5.8 tonnes of methaqualone powder - capable of making 11 million Mandrax tablets with a street value of US$100 million - on the ship Songa, which came from Hong Kong, on September 2. Sources said police had identified the mastermind behind the cartel and they were working to build a case against the unnamed Hong Kong-based drug lord. South African police spokesman Bala Naidoo said: 'This is the third consignment to be intercepted in the harbour in the last month and the recent trends indicate that drug smugglers are still active in smuggling drugs into South Africa and other African countries. 'We suspect the three consignments are linked and investigations of these three cases will be done as a single investigation. 'Our investigations are streamlined to identify the syndicate involved ... and thus far we have been able to identify those involved.' A Hong Kong police spokesman said the arrests of the seven men with 2.1 tonnes of methaqualone had provided police with a vital breakthrough in the investigation.