Cooperation with other countries is being intensified to combat arms smuggling, according to an official at the General Administration of Customs.

Last year, Chinese customs officials investigated 50 cases of smuggling involving firearms and ammunition, an increase of 16.3 percent from the previous year.

Authorities confiscated 5,916 guns, 882 gun parts and 13,000 rounds of ammunition in these cases.

"The smuggling of drugs or firearms poses serious threats to national security and public safety. We have intensified controls and carried out several special operations to prevent it," said Xu Wenrong, deputy director of the anti-smuggling bureau at the General Administration of Customs.

"Our priority is to safeguard national security and social stability," Xu said.

Most of the confiscated firearms came from the United States via international express freight companies, he said.

"Firearms smuggling has been conducted by criminal gangs, with gang members assuming different tasks to form an intelligent, professional and premeditated organization," Xu said.

The US smugglers who supplied the guns and submitted false customs declarations sent the arms through major express freight companies. Middlemen collected the packages and delivered them to buyers across China for large profits, he said.

The weapons from the US, which included pistols and air guns, ended up with Chinese suspects who collected the weapons to trade or use in violent crimes, Xu said.

Customs officials in Hangzhou, the capital of Zhejiang province, said that from May to September 2013 during routine checks at a post office they discovered two suspicious packages from the US sent via express mail.

Anti-smuggling officers confiscated eight pistols, 33 gun parts and 3,259 rounds of ammunition from the packages. They also arrested two people to whom the mail was addressed for alleged involvement in smuggling, the customs administration said.

Wang Beijing, director of the administration’s international enforcement cooperation office, said suspects in the US colluded with Chinese partners mainly through the Internet, posting pictures online, discussing prices and transferring money. Smugglers in the US then declared the guns as machinery equipment to pass customs checks and sent them to Chinese collectors or middlemen.

Sending forbidden items through international express mail meant they avoided Chinese authorities, Wang said.

"Sometimes, although we intercept illegal firearms at the scene, we can’t trace the shipments back to the source. This is because the identification and addresses provided are false. Chinese suspects also pay for others to fetch the parcels," she said.

Chinese and US authorities are attempting to combat such cases of firearms smuggling.

In November, the Foreign Ministry and judicial authorities will hold an annual ministerial-level joint law enforcement meeting with their US counterparts to discuss major concerns including illegal immigration, the extradition of fugitives and cooperation on individual cases.

This year, a special section will also be established between China’s customs authority and its US counterpart to target gun smuggling.

Xu said: "Once they have any clues, Chinese anti-smuggling officers will notify their US partners, who won’t act immediately on the suspects. They’ll allow the illegal goods to pass so that they can home in on the smugglers and destroy the criminal rings."

China and the US will also widen their intelligence-sharing, hold joint campaigns to strengthen checks on mailed cargo, and sign agreements with express mail companies to improve monitoring of senders’ information.

The administration will also cooperate with other parties, including the public security and border control agencies, to build an information-sharing platform to collect clues and establish a list of suspected smugglers.

Li Fang, a lawyer from the criminal defense committee under the All-China Lawyers Association, said the strict control of, and severe punishment for, firearms smuggling in China had caused suspects to look overseas to illegally obtain items for trading.

"Some guns and ammunition were even flowing into the hands of terrorists," she said.

"The priority is to enhance the intelligence-gathering capability," Li said, adding that it is necessary to build an information-sharing platform between customs authorities and other sectors.