It is the greatest mystery in aviation history.

Today, 100 days since it vanished on a routine flight from Kuala Lumpur to Beijing, there are still no answers to the fate of Malaysia Airlines flight MH370 and its 239 passengers and crew.

Malaysia - which has copped heavy criticism for the delays and confusion surrounding what many say was a bungled initial search - vowed there would be no let-up in the search.

"We cannot and will not rest until MH370 is found," Acting Transport Minister Hishammuddin Hussein said. "We cannot and will not abandon the families of the crew and passengers of MH370."

As long as there's a sliver of hope, I won't give up on you

GAO YONGFU'S DIARY

He expressed gratitude to Australia, China and other countries that had joined the search, which remains focused on the southern Indian Ocean.

"Indeed, as the search transitions to a more challenging phase, we reaffirm our commitment with renewed vigour to locate the missing MH370," Hishammuddin said.

And he said that despite the criticism, "Malaysia will be credited for doing the best to our abilities under near-impossible circumstances and history will judge us favourably for that".

Malaysian Prime Minister Najib Razak reiterated Malaysia's commitment to the search.

"On this hundredth day since MH370 went missing, remembering those on board and their families," he said on his Twitter account.

But their words were of little comfort to the relatives of the missing passengers, including Gao Yongfu, the wife of one of the 154 Chinese passengers on board. Since March 8 - the day MH370 disappeared with her husband, Li Zhi, on board - the Tianjin woman has kept a diary of her sometimes conflicting emotions.

The diary - excerpts of which are published in the Post today - chronicles the increasing confusion, anxiety and despair of a wife who may never know how her husband died.

Yet Gao refuses to give up on a miracle. "As long as there's a sliver of hope, I won't give up on you," she writes in one entry.