SHIJIAZHUANG, Jan. 5 (Xinhua) -- Customs staff and police officers in north China's Hebei Province have caught 16 suspects smuggling hundreds of luxury cars to China, local authorities said Friday.

The suspects confessed to illegally transporting more than 320 limousines, such as Rolls-Royces, Bentleys and Ferraris, worth around 331 million yuan (51 million U.S. dollars), according to Shijiazhuang City customs.

Police received a report a man surnamed Wu was suspected of smuggling limousines at the end of 2016, and last April more than 80 police and customs officers launched a joint operation, catching 16 smugglers.

The investigation is ongoing.

Last year, Chinese customs launched the "Sword Guarding the Country's Gate 2017" campaign, to take tough measures against smuggling. The Shijiazhuang customs handled around 400 smuggling cases in the campaign.