Two waves of devastating floods mostly in Malaysia's south have seen damages of at least RM1.5 billion, the government said today.

Deputy Prime Minister Najib Abdul Razak said the figure did not include estimates of personal and commercial damages, signalling losses were set to skyrocket further.

"We have discovered that the damages in terms of the government's account, which includes rehabilitation, damaged infrastructure and others, is at least RM1.5 billion," Najib told reporters.

"These damages do not include personal and commercial losses," he said.

The figure includes repairs to infrastructure, including roads and bridges, which will cost some RM350 million, he said.

The worst-hit state of Johor in Malaysia's south experiences annual flooding, but residents have said the recent floods, which saw rivers bursting banks amid massive drainage problems, were the worst in a century.

The first wave of floods which started in late December forced 134,00 people to flee their homes in Johor, while the second in early January saw 148,000 people evacuated, according to government figures.

Eighteen people have been killed in the floods, mostly in Johor.

Suffering farmers

"The floods this time were more severe and more widespread in the state of Johor," said Najib, adding authorities are discussing future flood mitigation plans.

Over 30,000 people are still in sheltering in relief centres in one of the worst-hit districts of Batu Pahat in Johor, where flood waters are only slowly receding, the state Bernama news agency said Monday.

Flooding has also caused damage and forced evacuations in western, central and eastern states on Borneo island.

Malaysia's agriculture sector has also been severely damaged, with thousands of farmers and livestock breeders suffering losses of tens of millions of ringgit, according to the government.

However, Najib sidestepped questions on the overall impact of the floods on Malaysia's economy, vowing instead the government would help affected businesses.

"There are schemes that we will undertake. We are trying to coordinate between (the central bank) and the trade ministry to help small businesses, traders and others who are affected," he said.