Washington - Two days after a United States submarine sank a Japanese fisheries training boat off Honolulu, no trace had been found of the nine missing, who were thought to have been trapped below decks on the Ehime Maru.
The submarine, the USS Greeneville, was practising an emergency ascent when it slammed into the Ehime Maru, the US Navy said. Japanese Prime Minister Yoshiro Mori and Foreign Minister Yohei Kono called for the raising of the training vessel, which sank in 550m of water.
Admiral Thomas B Fargo, commander-in-chief of the US Pacific Fleet, told reporters in Hawaii that the crew was "using the emergency main ballast tank blow - an operation we do on a regular basis".
The Ehime Maru, with 13 second-year ocean engineering students, two teachers and 20 crew, sank within 10 minutes of being hit, about 16km south of Diamond Head, off Honolulu.
Twenty-six survivors were fished from lifeboats but four students, the two teachers and three crew were still missing.
The US Navy and US National Transportation Safety Board have launched an investigation, and the submarine's commander has been suspended from duty.
The Greeneville flew its US flag at half-mast as it returned to Pearl Harbour, and televised images showed a dent and long gashes, up to 20m, along one side of the submarine.
Fargo said the area where the accident happened was open to civilian and navy ships, and the Ehime Maru had done nothing wrong.
Its captain, Hisao Onishi, said the submarine had surfaced very suddenly in an area where he had never before encountered submarines.
Submarine experts said the navy crew may have failed to check if a boat was above them, or the Ehime Maru may have been hard to detect, for example if its engine had been off and it had not made any noise.
Reports quoted Onishi as saying the submarine's crew had done nothing to help the shipwrecked. Fargo rejected this, saying a submarine could not open its main hatch with two-metre-high waves around it.
When practising an emergency ascent, a sub is supposed to first surface, visually ensure the area is clear, and then re-submerge before making the rapid ascent, US reports said. It must also use its microphones in an acoustic search prior to surfacing. - Sapa-DPA