Malaysian Prime Minister Najib Razak has said his country remains committed to finding flight MH370, on the first anniversary of its disappearance.
Relatives of the 239 missing passengers and crew are holding a series of remembrance ceremonies.
The Malaysian airliner was flying from Kuala Lumpur to Beijing when it vanished. No trace has ever been found.
Meanwhile, the Malaysian government has released its official report into the disappearance of flight MH370.
The BBC's Jonathan Head says the report contains masses of technical information about the missing aircraft, its maintenance record, the background of the crew, and the various air traffic control and military radar tracking records of the plane.
However, he adds, it appears to offer no significant new information which might explain where the plane went, or what happened to it.
Difficult to bear
"No words can describe the pain the families of those on board are going through. The lack of answers and definitive proof - such as aircraft wreckage - has made this more difficult to bear," said Mr Najib in a statement.
He added that the search team had followed the "little evidence that exists" but remained "hopeful" that the plane would be found.
The international search team is focusing on an area of the southern Indian Ocean, approximately 1,600km off the coast of western Australia.
Earlier on Sunday, the families of MH370 crew members held a remembrance ceremony at the house of missing in-flight supervisor Patrick Gomez.
"We're always thinking exactly what happened on that day itself, you know the conversations that we were having, the tears, the hugs that we were giving each other," said his wife, Jacquita Gonzales.
The BBC's correspondent in Kuala Lumpur said that the event had not been billed as a commemoration ceremony because many family members still believed that their loved ones were alive.
Earlier, Malaysia's Transport Minister Liow Tiong Lai said that he was confident that the plane would be found in the southern Indian Ocean.
Mr Liow promised his government would continue to back the search and said he was confident they could complete the search operation "hopefully by May this year".
He told AFP news agency that investigators would go "back to the drawing board" if the search failed to yield results by May.
Some families of those on board the plane have accused the Malaysian authorities of hiding some information, but the transport minister urged them not to believe the conspiracy theories.
Earlier this year, the Malaysian government declared flight MH370 to have been lost with all on board, in a move it said was necessary to start processing compensation claims for the families.
Widow wants to know the truth
New Zealander Danica Weeks said she wanted to tell her two young sons the truth about what happened to their father - mining engineer Paul Weeks - on Flight MH370 a year ago today.
But Mrs Weeks - who lives near Perth - said she could not do that because she and the rest of the world do not yet know what happened to the Malaysia Airlines plane.
Mrs Weeks told a Perth news website she needed to know where the plane and her husband are before talking about it with the children.