A U.S. Navy "black box" detector made its much-anticipated debut in the oceanic hunt for flight MH370 on Friday but Australia's search chief warned it was crunch time with the box's signal set to expire soon.

As the extensive search wore on, Malaysian opposition leader Anwar Ibrahim said he believed the country's long-ruling regime was concealing information on the crisis, saying "the government knows more than us."

Malaysia will not rest until it can give answers to the distraught families of those on board missing Flight MH370, Prime Minister Najib Razak said Thursday, admitting the search was a "gargantuan" challenge.

International efforts to find any sign of the Malaysia Airlines plane which vanished on March 8 have so far failed, but search coordinator Australia says there are no imminent plans to abandon the operation.

Malaysia's top police official warned Wednesday that authorities may never learn what caused the mysterious disappearance of flight MH370, as he indicated a three-week-old criminal investigation has so far been inconclusive.

"Give us more time," Inspector General of Police Khalid Abu Bakar told reporters in Kuala Lumpur, according to Dow Jones Newswires.

Malaysia revealed the full radio communications with the pilots of its missing flight Tuesday, but the routine exchanges shed no light on the mystery as an Indian Ocean search for wreckage bore on with no end in sight.

The previously unreleased conversations between MH370's pilots and air traffic controllers had been the subject of much speculation as suspicions have focused on whether one or both of its pilots deliberately diverted the plane on March 8 with 239 people aboard.

Philippine President Benigno Aquino vowed Monday to push through with a U.N. appeal to solve its maritime disputes with China, as Beijing warned of consequences.

"We are not here to challenge China, to provoke them into any action, but I do believe that they should recognize we also have the right to defend our own interests," he told reporters.

Malaysian Prime Minister Najib Razak will travel to an Australian air force base near Perth to observe the multi-nation search for missing flight MH370, his government said on Monday.

Transport and Defense Minister Hishammuddin Hussein said Najib would make the trip on Wednesday.

Malaysia's transport minister vowed Saturday to continue the search for "possible survivors" from a missing passenger plane, three weeks after it crashed in the remote Indian Ocean.

"No matter how remote the odds, we will pray, hope against hope, and continue to search for possible survivors," Hishammuddin Hussein told reporters during a condolence visit to relatives of Malaysian passengers and crew.

Human rights group Amnesty International said Thursday that Japan's use of capital punishment was "shrouded in secrecy" and criticized its treatment of death row prisoners who are kept in solitary confinement for years.

Launching its annual review of the death penalty around the world, Amnesty said the United Nation's Committee Against Torture has signaled its concerns about the Japanese criminal justice system.

Thunderstorms and gale-force winds grounded the international air search for wreckage from Flight MH370 on Thursday, frustrating the effort yet again as Thailand reported a satellite sighting of hundreds of floating objects.

The Thai report was the second in two days suggesting a possible debris field in the stormy southern Indian Ocean from the crashed jet.

Fresh satellite images taken during the search for a missing passenger jet show 122 "potential objects" in one area of the Indian Ocean, Malaysia said Wednesday.

The images from Airbus Defense and Space in France show the objects in a 400-square-kilometer (160-square-mile) area of the ocean, said Transport Minister Hishammuddin Hussein.