Floods in Malaysia caused by heavy rains have left a teenager dead and forced authorities to evacuate thousands of people, officials said Wednesday.

Some 19,000 people have been relocated to evacuation centres set up in schools in the east coast states of Pahang and Terengganu and Johor in the south, an official and news reports said.

A 17-year-old boy who was fishing with his father in Terengganu drowned after being swept away in a swollen river, a state police official said.

A Meteorological Department official said river levels continued to rise due to the high tide and water being released from dams, but the body expected rain to ease in the flood-hit areas.

"It's still raining today, but we expect the rain to stop by tomorrow," he told AFP. "Then the situation will improve."

The department issued an "orange" alert for Pahang and Terengganu on Monday, warning residents to be prepared for a possible evacuation.

Floods caused by annual monsoon rains that begin around November are common in the Southeast Asian country.