Malaysia and Australia said they remained "hopeful" of solving the mystery of flight MH370 as the second anniversary of the plane's disappearance arrived Tuesday with no end in sight for devastated families.

The anniversary will be marked in Malaysia with the release of a progress report by investigators probing the baffling case, but it remained unclear whether it would contain any new revelations.

Malaysian Prime Minister Najib Razak said authorities conducting a painstaking and still-fruitless search for a crash site in the Indian Ocean remain committed to solving the "agonising mystery".

"The current search operation is expected to be completed later this year, and we remain hopeful that MH370 will be found," he said in a statement. 

If the search fails, Malaysia, Australia and China will meet "to determine the way forward," he added.

The Malaysia Airlines jet vanished on March 8, 2014 en route from Kuala Lumpur to Beijing with 239 passengers and crew onboard, mostly from China and Malaysia. Authorities believe it flew far out over the remote southern Indian Ocean and went down.

The three nations have already indicated they will end the biggest and most expensive search effort in history if nothing is found on the seafloor in the designated search area. 

That zone is expected to be fully scoured within a few months.

Next-of-kin, struggling for closure in the tragedy, have pleaded for the quest to continue beyond that.

Australian Transport Minister Darren Chester also said Tuesday that the three countries remain "hopeful".

"Finding the aircraft would give answers to the world, in particular the families of missing loved ones, about what happened," he said.

  Investigators to issue statement

 The team of international investigators set up in the wake of the disappearance will issue its progress report at 3:00 pm (0700 GMT). The update is required under international rules regardless of whether there is anything new to report.

The team's initial report, issued a year ago on the first anniversary, shed no light on the perplexing mystery.

Theories to explain the disappearance include a possible mechanical or structural failure, a hijacking or terror plot, or rogue pilot action.

Malaysia's parliament observed a minute's silence for the anniversary but there were otherwise no major public events in the country.

In Beijing, at least 20 Chinese relatives of those on board gathered at a major Buddhist temple to pray and shout slogans such as "Malaysia, return our loved ones!" under the watchful eyes of scores of police.

Several fell to their knees and bent their heads to the ground in prayer, burning joss sticks in their hands.

Many families accuse the airline and Malaysian government of letting the plane slip away through a bungled response, withholding information on what happened, and treating grieving relatives insensitively.

The second anniversary also is the deadline for filing lawsuits against the airline.

Scores and perhaps hundreds of next-of-kin have filed lawsuits seeking damages in recent days in the United States, Malaysia, China, Australia and elsewhere, while others have accepted undisclosed settlements, say attorneys.

The flag carrier on Tuesday denied the charge of insensitivity toward next-of-kin and promised to honour its "moral and legal obligations."

"(Malaysia Airlines) has never shied away from its commitment to engage with the next-of-kin, and strives in good faith for payment of fair and equitable compensation," it said in a statement to AFP.

A wing fragment which was later confirmed to be from MH370 was found on an island thousands of kilometres from the search area last July, the first proof the plane went down.

Two new pieces of debris have been found recently. But they are yet to be confirmed as from the aircraft and such flotsam is anyway no help in pinpointing a crash site.