Malaysian Prime Minister Najib Razak will travel to Perth on Wednesday to observe search operations firsthand, Malaysia's Acting Transport Minister Hishammuddin Hussein said on Monday.

Mr Najib will be there to "thank everyone involved in search", Mr Hishammuddin said at a press briefing.

Echoing Australian Prime Minister Tony Abbott's earlier remarks, Mr Hishammuddin said the international cooperation in the search is "nothing short of tremendous".

The Australian vessel Ocean Shield, fitted with a device known as a towed pinger locator and an underwater drone equipped with electronic sensors for detecting the black box's signal, will arrive at the search area on Thursday, he said.

The search area on Monday covered 254,000 sq km, he added.

Five objects - all not related to MH370 - were spotted on Saturday. Objects spotted on Sunday by Australian and Korean aircraft have yet to be identified, the minister said.

Mr Hishammuddin said he will be attending a defence meeting in Hawaii to seek specific military assets if a more advanced search phase is needed.

Reiterating that Malaysia understands many families of passengers onboard MH370 want to see physical evidence before they can accept that the flight had ended in the Indian Ocean, Mr Hishammuddin said: "Malaysia promises it will not give up hope, will continue searching."

"We will never give up," he said.

Mr Abbott had said earlier on Monday the search for MH370 had no time limit, despite three weeks of fruitless searching.

Mr Abbott also rejected suggestions Mr Najib had been too hasty to break the news even though no confirmed wreckage from the plane has been found.

"The accumulation of evidence is that the aircraft has been lost and it has been lost somewhere in the south of the Indian Ocean," he told reporters at the Perth military base coordinating the search.

"The accumulation of evidence is that the aircraft has been lost and it has been lost somewhere in the south of the Indian Ocean," he told reporters at the Perth military base coordinating the search. - See more at: http://sph.straitstimes.com/breaking-news/se-asia/story/overwhelming-ev…

"That's the absolutely overwhelming wave of evidence and I think that Prime Minister Najib Razak was perfectly entitled to come to that conclusion, and I think once that conclusion had been arrived at, it was his duty to make that conclusion public."