The eight, including six mainland Chinese citizens, a Hong Kong resident and a Filipino national, were arrested earlier this month, said Liu Yuejin, head of the anti-drug bureau at China's Ministry of Public Security.

Ringleader Cai Aishan, who was arrested in Beijing on June 3, had been running drug-making factories in the Philippines producing the crystallised form of methamphetamine, also known as "ice", since 2004, Liu said.

Philippine police also seized 10 tonnes of chemicals used to make the euphoria-inducing drug when they stormed one of the ring's factories and two warehouses, Liu told a news conference.

The ring netted more than 10 million yuan ($1.3 million) in profits by selling 30 kg of the drug in November, Liu added.

Five of Cai's accomplices were arrested in 2005 when they were trying to smuggle 192 kg of the drug to the Philippines through Hong Kong, Liu said.

Under Chinese law, anyone found guilty of producing or dealing in 50 grams or more of the drug can face the death penalty.

In December, a court in the southern Chinese city of Guangzhou sentenced a man to death for making 12 tonnes of the drug between 1998 and 1999.