In this file photo shows Royal Australian Air Force Loadmasters Sgt Adam Roberts, left, and Flight Sgt John Mancey, launch a Self Locating Data Marker Buoy from a C-130J Hercules aircraft in the southern Indian Ocean. Picture:Australian Defence Department, Justin Brown, File

Sydney - Ships were steaming to a new search area on Saturday to hunt debris from a Malaysia Airlines jet that disappeared three weeks ago shortly after takeoff from Kuala Lumpur.

A device to help locate the flight recorders was on an Australian ship and en route to join five other vessels in the search area.

Five of the 10 planes that left Perth on Friday spotted what could be remnants of the Boeing 777-200. They were the first sightings since the search shifted more than 1 000 kilometres north to a region 1 680 kilometres west of Perth.

The search was moved after data analysts said the plane was travelling faster than first thought and so would have run out of fuel sooner, meaning any debris would likely be further north.

With the hunt now centred nearer to Perth, planes can search for longer over waters that are calmer and not as deep. Being out of the infamous Roaring Forties also means the weather is more favourable for the eight aircraft that took off on Saturday. “We shouldn't underestimate the difficulty of this work,” Prime Minister Tony Abbott said in Perth.

“These are inhospitable seas. We're trying to find small bits of wreckage in a vast ocean.” The Australian Maritime Safety Authority warned in its latest bulletin that many supposed sightings may prove false. “It's not known how much flotsam, such as from fishing activities, is ordinarily there.

At least one distinctive fishing object has been identified,” it cautioned. The agency, managing the search on behalf of the Malaysians, has about a week to find the so-called black boxes before their batteries fade and their signals give out. - Sapa-dpa