At least 21 people have been killed and eight others are missing after the worst flooding in decades across Malaysia's northeast, police said on Wednesday, with almost a quarter of a million people displaced.

They said 14 of the deaths were recorded in the worst-hit state of Kelantan, where some 158,476 people were displaced.

Four people died in Terengganu and three in Pahang state. There are also reports of outbreaks of flu and diarrhea.