By Joyce Lee

SEOUL (Reuters) -Seven people have died, three were missing, seven injured and thousands evacuated in South Korea on Saturday, officials said, as a third day of torrential rains caused landslides and the overflow of a dam.

As of 11 a.m. (0200 GMT), 1,567 people had been evacuated nationwide, according to the Ministry of Interior and Safety, and the number could rise as water overtopped the dam in North Chungcheong province.

Local governments' evacuation orders covered more than 7,000 people at various times, according to provincial authorities.

As of 9 a.m., more than 2,700 tonnes of water per second was flowing into Goesan Dam, the maximum it can discharge.

Korea Railroad Corp said it was halting all slow trains and some bullet trains, while other bullet trains might be delayed due to slower operation, as landslides, track flooding and falling rocks threatened safety.

A slow train derailed late on Friday when a landslide threw earth and sand over tracks in North Chungcheong province, the transport ministry said. The engineer was injured, but no passengers were on board.

In a meeting with government agencies on Saturday, Prime Minister Han Duck-soo called for the military to actively join in rescue activities, working with government officials to mobilise equipment and manpower.

(Reporting by Joyce Lee; Editing by Michael Perry and William Mallard)