THE 519 passengers and crew of an ocean-going gambling ship had to be rescued by Royal Navy and police launches last night after a blaze broke out on the vessel. One navy ship, three fire boats and 18 police launches were involved in the evacuation of the 4,800-tonne, Panamanian-registered New Orient Princess, which was 1.5 nautical miles off Tung Lung Chau when the fire broke out at about 9 pm. The ship had left Kowloon Bay shortly after 8 pm on its regular nightly gambling excursion into international waters off Hong Kong. But punters were soon scrambling for safety after the blaze broke out in a sauna. Two crew were slightly injured during the rescue and were admitted to Tang Shiu Kin Hospital after being brought ashore at the Sai Wan Ho marine base. The fire ships and six New Orient Princess officers, including the captain, who stayed aboard were still fighting the fire early this morning. ''No flames could be seen but there was a thick column of dense smoke still billowing out from the stern of the vessel,'' a witness said. The vessel has been operating nightly, two-hour gambling trips for about 18 months. It features four floors of gambling facilities, where punters can enjoy a wide variety of games not normally available in the territory because of its strict gambling laws. Two mainland seamen said they were working in the kitchen when they heard a ship's broadcast telling passengers and crew that a fire had broken out and to assemble in the restaurant. When they reached the restaurant, they could see smoke pouring from the stern of the ship. One passenger said he had seen smoke coming from a ventilation shaft and told a crew member. ''An announcement was broadcast informing passengers that a small fire had broken out, but there was nothing to fear. The broadcaster urged passengers to continue singing at the karaoke bar,'' he said. ''A few minutes later a second announcement was broadcast asking passengers and crew to gather in the vessel's restaurant.'' Marine Police divisional commander Superintendent Kong Shing-shun said they received a report of a fire at 9.04 pm. Within minutes, a Marine Police launch reached the scene and reported that two life rafts had been lowered and thick smoke was coming from the ship. Owned by Panamanian shelf company Golden Chances, New Orient Princess passed a full port state control examination two months ago and was issued a valid safety certificate. The examination included detailed inspections of fire and safety conditions, life rafts, radio equipment, structure and crew qualifications. Assistant Director of Marine John Tse Yan-chi said the department would investigate the fire. The Merchant Shipping (Safety) Amendment law, which allows the Marine Department to mount full surveys of casino ships, was only gazetted this year after operators fought a three-year battle to prevent Marine Department inspections. There are, at present, three other casino ships - Queen of Jin Jiang, Delfin Star and Southern Kingdom - operating out of Hong Kong. Although gambling is illegal in Hong Kong and despite repeated calls to close legal loopholes allowing casino ships to operate, the Government has yet to act. However, finishing touches are being made to a stiff licensing system for seaborne casinos under the Gambling Ordinance, which prevents private gambling for profit. The full details are being kept under wraps for fear of alerting casino ship owners to possible loopholes in the law.