The United States has stepped up its crackdown on illegal transshipments through a revision of bond payments imposed on importers, according to a trade expert. A senior economist for the Hong Kong Trade Development Council, Michael Martin, said the new policies - introduced on May 1 - were a toughening of the US stance. US Customs has imposed a bond equivalent to half the value of textile imports and textile products with a minimum of US$50,000. This means a trader who imports $5 million in textiles and apparel claimed to be produced in Hong Kong must have a continuous bond set at $2.5 million. Mr Martin said: 'In the past, the US authorities did not get into whether the level of bond was high enough, but now they want the size of the US bond to be comparable to the size of the trade.' US Customs has said it is satisfied with the progress being made by its Hong Kong counterparts in identifying and prosecuting companies engaged in illegal transshipments. On May 1, US authorities lifted single bond requirements on eight categories of textile products but announced a review that has led to the new continuous bonds. The impact on US importers is unclear. Higher bonds and more administration could make the territory's exports less attractive to some importers, but the extent of any downturn would depend on other factors such as alternative sources. Research has found demand for about 70 per cent of textile products affected by additional US bond requirements fell last year.