CHINA has moved to defend its detention of Vietnamese ships, saying foreign vessels were making false reports of piracy by officials to hide failed smuggling runs. In China's strongest statement on the controversy, the director of the Guangdong Public Security Bureau, Mr Chen Shaoji, said yesterday he had ''more than enough'' evidence to justify the seizing of ships and the detaining of cargos. Seamen were ''double wrapping'' - disguising the labels on China-bound cargo by wrapping goods with the names of Vietnamese ports but with Chinese destinations underneath. Unclear navigation charts and new destinations given to ships by agents once vessels were under way were other techniques used. Captains and crew had provided evidence in testimonies, Mr Chen said. ''Recently, smuggling by tai feis [speedboats] has gone down. But [we have noticed] a very important trend of [smugglers] switching to foreign-registered freighters,'' he said. ''They often used descriptions such as pirates and sea robbery committed by public security officers to hide their criminal activities.'' He referred to a maximum of 10 ships having been detained. Marine Department figures list at least 36 suspected interceptions since last September. Mr Chen said China had concentrated on only a tiny percentage of shipping that was smuggling. It would not hurt law-abiding businessmen, he said. Security Branch officials, however, said yesterday they had not received detailed evidence from China and noted that ships were leaving with correct manifests. The Government had no reason to doubt explanations from seized ships, while it had received little detail from China authorities despite recent requests lodged through the New China News Agency, he said. The branch had earlier this week been instrumental in the Marine Department playing down harassment and piracy claims at a United Nations meeting in London, and stopped the department naming China. Agents involved in the Hongkong to Vietnam trade challenged the Chinese to give evidence. ''The trade is legal and the goods are going to Vietnam and it's clear that China has no control of the officers patrolling outside Hongkong,'' said a spokesman for Scarbrook Shipping. Scarbrook still has one ship in detention out of a string of ships and cargo seized and later released. ''We just don't understand why they have taken so long to say this,'' he said. Mr Chen said the Public Security Bureau was appealing against a decision by a court in Zhanjing, Guangxi province, which upheld a complaint from a Hongkong freight company, but he did not have details.