Malaysian and Australian prime ministers on Thursday pledged again to do everything humanly possible to find the lost Malaysian Airlines MH370 jetliner, although they cautioned that they cannot be sure of success.
Malaysian prime minister Najib Razak, who is on a short visit to Perth to observe the search operations and personally thank those involved, said a new refined search area had given "some hope" but did not give further details.
International experts believe that the plane may have gone down in the rough waters off Perth on March 8, hours after it took off for Beijing. It is still unknown why the plane had diverted so far off its course.
Mr Najib, who thanked Australia for leading the search in its waters, said despite the large number of ships and aircraft out searching everyday, the search area is vast and the work is not easy.
"It is one of the great mysteries of our time," he said, describing it as a Herculean task as there was so little evidence.
He promised the families that Malaysia would not give up the search.
Speaking at a joint press conference in Perth, Australian prime minister Tony Abbott also promised that Australia will not rest until it has done everything it humanly can in the search for the plane that went missing with 239 people on board almost a month ago.
He said they cannot be "certain of ultimate success" in finding the plane but all countries were doing their best in very difficult conditions.
Mr Abbott also appealed to the families to be patient, and said Australia will extend its warmest possible welcome to them when it comes to the time for them to arrive in Perth. Malaysia Airlines has promised to fly the families to Perth when the authorities give the green light to bring the families to the search site.
Mr Najib had earlier toured the search base in Perth, after he arrived late Wednesday night.