HUMAN error is believed to have caused the collision between two Panamanian ships in thick fog off Hongkong yesterday. The container ships Marine Brave and Wing Lee No 1 were separated in an eight-hour operation and returned to Hongkong under Royal Navy escort last night. Their captains, from Germany and Hongkong, will face an inquiry today by the Panamanian Consulate. Senior Marine Department officials were privately critical of the accident, which occurred at 6.30 am, but have no jurisdiction to investigate because the collision happened in international waters, 63 miles (about 100 kilometres) northeast of the territory. ''Royal Observatory fog warnings had been issued and these ships have radars and clear international conventions setting out the precautions necessary in poor visibility,'' said one official. ''Somebody wasn't doing their job properly.'' Department Senior Marine Officer (Search and Rescue), Mr Philip Weaver, said fog clearly contributed to a ''text-book collision''. ''It will probably come down to human error,'' he said. ''Someone made the wrong decision and turned the wrong way.'' The bow of the 5,981-tonne Marine Brave, returning from Taiwan, smashed halfway through the 4,164-tonne Wing Lee, which was on its way from Hongkong to Taichung, Taiwan. The speed they were travelling is not yet known, but the force of the collision pushed containers around the decks of the Wing Lee, with one falling over the side. It is believed none of the Filipino and Chinese crew was injured. The two ships were freed at about 2.30 pm when the Marine Brave reversed and the Wing Lee moved backwards and forwards in a dead calm South China Sea. Water had to be pumped from the bows of the Marine Brave. The German captain of the Marine Brave stalled efforts to separate the ships until the Royal Navy patrol boat HMS Plover, alerted by the Marine Department, arrived. A Royal Navy medical unit and diving team were winched on to the Plover by helicopter. A Government Flying Services pilot, Aircraft Commander Wayne Parsons, said he could see only about 100 metres ahead of him when his Super King Air aircraft arrived on the scene at about 10.30 am. He flew over the scene for two hours speaking to both captains, who were talking ''in a civil manner''. ''In a distress situation there is no reason to be ungentlemanly,'' he said. ''It was really quite a successful operation, as there's always real potential for a mini-disaster. ''In the end, they looked like two large unwieldy objects waltzing across the sea.'' The Consul-General of Panama, Mr Raul Adames, said he would try to contact the captains, crews, owners, agents and lawyers today, but was unable to comment further. The incident closely mirrors the collision a year ago today between the Greek freighter Inchon Glory and the German passenger ship Europa, carrying 800 tourists. The ships were locked together for 24 hours after the bow of the Inchon Glory pierced the dining room of the Europa. The mishap occurred within 160km of yesterday's incident. Crew from the Inchon Glory spent the night on the Europa while salvagers used mattresses and bedding to plug up leaks on their ship, which was later towed to Hongkong. The Director of Marine, Mr Allan Pyrke, last night called on mariners to heed long-standing international conventions for movement in fog, requiring ships to travel at safe speeds and even to stop if conditions and equipment were unsafe. ''This is a time of year when fog is common in coastal waters,'' Mr Pyrke said. ''Extra caution in any sort of poor visibility must be taken.''