In a rare move, Pakatan Harapan chairperson Dr Mahathir Mohamad has commended Prime Minister Najib Abdul Razak.

Responding to Najib's call on all quarters not to politicise the devastating floods in Penang, the former premier said: “This is very good.”

"This (flood) not only affects Harapan parties or governments but everyone.

"We should think of it as a citizens' problem. So there should be no preference to the party concerned, blaming this government or that government. That shouldn't be the attitude of both citizens as well as the government," he added when quizzed on the premier's call.

In making the call, Najib said the focus should be on helping those affected by the flood and urged all government agencies and party machinery to join the effort.

Mahathir was speaking to reporters at the Penang airport this afternoon. His visit to the flood-hit state comes a day after Najib and his wife Rosmah Mansor's visit.

Continuous rainfall from Saturday to Sunday morning - the highest recorded in the state's history - triggered a massive flood which claimed seven lives.

As of this morning, over 3,000 people were still displaced from their homes due to the deluge.

Mahathir visited the victims still in flood relief centres, including those displaced in Kampung Terus, Penanti.

When met at the village, Mahathir told reporters that the flood was a good lesson for Malaysia to learn how to manage disasters.

At his press conference earlier in the day, the former prime minister remarked that more flooding could be expected in the future, citing global warming as one reason.

"When there is global warming, evaporation of the water is much more, the changes in the temperature at different parts of the world are different and the pressure is also different, so you have this extra rainwater plus stronger winds because of the differences in pressure between one place and the other.

"You can't do anything to reduce global warming, of course, US President Donald Trump doesn't believe in that but global warming is a reality.

"This is the kind of disaster that will happen again and again. So I think we need to think about how to deal with this disaster and find places where we can seek shelter," he said.