SHENZHEN - The southern coastal city bordering Hong Kong will increase its efforts to combat the smuggling of refined oil and the activities of itinerant smugglers, Shenzhen customs said on Friday.

On Friday, Wang Zhi, deputy chief of Shenzhen customs, reported on the department's anti-smuggling work in the first quarter. So far this year, the department has handled 46 criminal cases with a total value of more than 71 million yuan ($11 million).

Customs have also seized more than 3,000 grams of heroin, 343 tons of refined oil, 1,354 kilograms of silver and a large number of iPhones and other electronic devices.

Wang said that despite those seizures, customs officers still face severe challenges. The smugglers have developed a wide variety of methods and are becoming increasingly intelligent and professional.

Itinerant smugglers remain a major problem despite a crackdown on their activities. Meanwhile, the smuggling of popular electronic products is increasing, while drugs and weapons trafficking remain active.

According to Wang, the smuggling of refined oil is rampant as gasoline prices on the mainland continue to rise, providing easy profits for those smuggling the fuel from Hong Kong.

On March 14, Wang said Shenzhen customs seized a diesel-smuggling gang and confiscated 15 tons of smuggled fuel. To carry out their illegal trade, the gang used vans bearing Hong Kong-Guangdong license plates, which allow unhindered access between Hong Kong and the mainland.

The smuggling of electronic products, including iPhones and iPads, has been highly active and is mostly the work of itinerant smugglers. On March 13, a Shenzhen middle school student was seized at Shatoujiao Port by the customs. She had secured 25 iPhone 4S, worth more than 80,000 yuan, around her waist and legs. She had been promised just 200 yuan for the trip. The case attracted widespread public attention.

(For full story, please see March 23 China Daily, page 3)

The reporter can be reached at huangyuli@chinadaily.com.cn