Najib arrived in Kelantan, which has the biggest problems among eight affected states, following his return from Hawaii on Friday after public criticism he had been absent as flooding worsened.
On Saturday, Najib announced an additional 500 million ringgit ($143.31 million) will be spent to aid victims after the flood subsides, following an initial government allocation of 50 million ringgit two days ago. The number of people evacuated topped 160,000 at 0700GMT Saturday, according to the New Straits Times newspaper, a sharp increase from 100,000 a day before.
The prime minister attended briefings with the National Security Council, the National Disaster Management and Relief Committee, state government and local emergency responders, a statement on Friday said.
Taken during the 2007 Johor flood in Kota Tinggi, Malaysia, shot by Mr Tan, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license