Four foreigners may be executed in connection with one of the biggest drug-trafficking cases of this southern city bordering Hong Kong, according to Shenzhen Customs.

"The procuratorate of Shenzhen is ratifying the arrest of the four foreigners," Wang Yao, a customs press official, told China Daily yesterday. He gave no details about their nationalities.

The foreigners, along with five other suspects, have been in custody since they were caught for allegedly smuggling 144.5 kg of heroin from Pakistan in September, Wang said.

They are believed to be members of the same transnational drug-trafficking gang, according to Wang.

Customs officers got intelligence on Aug 20 that heroin would be stored in two containers of cotton yarn from Pakistan headed to Shekou port of Shenzhen.

While detecting no drugs in the first targeted container on Aug 22, the anti-smuggling enforcement team checked the second one arriving on Sept 2 and found 289 packs of heroin, each weighing 0.5 kg, hidden inside 6,720 rolls of cotton yarn.

After taking out the drugs, the officers let the goods continue to their destination - a warehouse in Guangzhou, capital city of Guangdong province and a one-hour train ride from Shenzhen.

One of the foreigners approached the goods on Sept 18 and was caught immediately.

The Hong Kong-based newspaper Ta Kung Pao reported yesterday that the chief of the transnational drug-trafficking gang was arrested in early December by customs in Pakistan.

China's Criminal Law stipulates that people trafficking more than 50 g of heroin are punishable by death.