United States trade officials are investigating claims traders in Hong Kong and other parts of Asia have been 'pressured' into concealing payment of illegal fees to have goods shipped to the US. The Federal Maritime Commission (FMC) is probing allegations that carriers have been 'selectively refusing' to provide space on ships unless the exporters pay higher or additional charges. In some cases, premiums of up to US$1,000 a container are said to have been paid. 'We are very concerned about these reports, which allege potentially unlawful activity on the part of the carriers at peak shipping season,' FMC chairman Harold Creel said. 'While this proceeding may ultimately result in prosecutions, our immediate aim is to put a stop to such unlawful practices.' The alleged offences are believed to have arisen because a surge in exports from Asia to the US has squeezed the available space on cargo ships. The FMC said smaller exporters with less bargaining power over rates were believed to have been targeted by some shipping lines for higher rates. Large accounts allegedly had been exempt from the additional or increased charges. But Manhattan Shipping Association president Marcus Wong said freight rates were increasing for exports from Asia to both US and European ports. 'I don't think it causes a problem. In the hard days, the shipping lines gave rebates and they might charge premiums in the good days,' Mr Wong said. US shipping law allows 'voluntary rate increases' only if the shipper and carrier mutually agree to amend their contract and file the terms with the FMC. The 90-day FMC investigation has the power to issue subpoenas, demand reports, and hold hearings that can compel witnesses to testify. Traders will be looking for a quick resolution of the problem because of the need to have goods delivered for the Christmas season. Under US shipping law, carriers with US trade goods have an obligation to act in a 'fair and non-discriminatory' manner. If they do not have sufficient space for the amount of cargo tendered, available space must be allocated equitably.