Customs officers are investigating whether a firm set up by a leading mainland state-run arms dealer is involved in the illegal shipping of strategic equipment to the Middle East. Officers visited the offices of Rex International Development twice last week. 'Inquiries have been made with the company concerning the shipment of the consignment to see if the plant equipment falls into the list of strategic commodities which need a licence for export,' a source said. The company was set up in 1982 by China North Industries Corp, or Norinco, and high-profile businessman Tsui Tsin-tong. Mr Tsui sold his 20 per cent stake of Rex International shares in 1988. Norinco owns 52 per cent of the company's shares. Mr Tsui is a director of Ocean Rex Shipping Company, owned by Rex International, Norinco and China Ocean Shipping. His brother, Terry Tsui Yam-tong, is a director of Rex International. A spokesman for Rex International declined to comment. The Tsui brothers could not be reached for comment yesterday. Norinco is a mainland government-run firm accused by US federal agents of being involved in smuggling 2,000 AK-47 assault rifles to America last May. Another top mainland arms merchant, Polytechnologies Ltd, was also accused of involvement. Both companies denied the accusation.