Updated at 4.12pm:\nCustoms have smashed a smuggling operation that had used a fishing vessel to transport illegal VCDs, a spokesman said on Thursday. It is the largest operation of its kind to be uncovered so far this year, he said. The VCDs were worth about $3.68 million. Officers arrested four mainland crewmen, aged 18 to 43, during the operation at midnight on Tuesday. The mainlanders have been charged and were to appear in the Eastern Magistrates' Court later on Thursday. Customs intercepted a suspicious fishing vessel while out on patrol on Tuesday, the spokesman said. 'The vessel was heading out of Hong Kong in waters off Tat Hong Point. It was heading towards the mainland,' he added. Custom officers searched the vessel and discovered a compartment holding 184,000 VCDs in the engine room. The maximum penalty for 'attempting to export unmanifested cargo' is a fine of $2 million and seven years' imprisonment, the spokesman said. He said the vessel involved in the offence would be confiscated.