SYDNEY: An underwater sonar vehicle used in the search for missing Malaysia Airlines plane MH370 has now been lost to the deep ocean floor after hitting an undersea volcano, Australian officials said Monday. The “towfish,” pulled behind a search ship and fitted with survey instruments, plunged to the bottom of the remote southern Indian Ocean on Sunday. “The towfish collided with a mud volcano which rises 2,200 meters from the sea floor resulting in the vehicle’s tow cable breaking,” the Joint Agency Coordination Center (JACC) announced. “The towfish and 4,500 meters of cable became separated from the vessel and are now resting on the sea floor,” the statement added. Australia is leading the search for the Boeing-777 that vanished on March 8, 2014 en route from Kuala Lumpur to Beijing with 239 people onboard. The aircraft is thought to have crashed after diverting from its course but the undersea hunt has so far found no sign of it.