Express delivery has become a major channel for drug traders to transport drugs, Shanghai customs said.

According to the customs, more than 90 percent of drug cases cracked this year were transacted through express delivery. In November alone, it cracked seven drug cases and confiscated more than 5.6 kg of drugs, including marijuana, heroin and cocaine.

Officials said it’s easier for drug traders to hide their personal information and address when using delivery.

So far, Shanghai customs has urged express companies to strengthen efforts on checking parcels.

This year, Shanghai customs has confiscated a total of 50 kg of drugs.