A ROYAL Navy patrol vessel passed within 500 metres of a Chinese military speedboat in Hong Kong waters to thwart a possible interception of fishing boats on Tuesday night. Captain-in-Charge of the Royal Navy in Hong Kong, Tom Sunter, said Chinese vessels had the right of innocent passage through Hong Kong but the navy would ''offer navigational assistance'' to the mainland military when it suspected a vessel could be boarded within local waters. ''When they saw the patrol vessel, the speedboat departed at high speed - about 30 knots - back into Chinese waters, so we're not really sure what was going on. ''It certainly seemed to jog his memory as to the navigational problems they were having.'' The speedboat, piloted by men in green uniforms, sped up to a fleet of mainly local fishing boats leaving Hong Kong about one kilometre inside local waters near Waglan Island. The HMS Starling was on patrol near the fleet at the time. The vessel left before communicating with the navy or the fishing boats. Meanwhile, the Hong Kong Government has yet to receive clarification from China about the freighter Tequila seized by Chinese speedboats at anchor within Hong Kong waters a month ago. The South China Morning Post found the ship and crew under detention in Zhuhai but the Government is waiting for more information from China before mounting a formal protest. Hong Kong has been told unofficially by mainland officials that the ship, carrying cars, was seized on an anti-smuggling raid but in Chinese waters. Radar printouts show the ship was in Hong Kong waters at the time.