Hundreds of South Koreans were forced to flee a wildfire fuelled by strong winds that burned parts of an eastern coastal city, destroying dozens of homes before being slowed by rain.

It took eight hours and nearly 3,000 firefighters to put out the blaze that started on a mountain in a central part of Gangneung at around 8:30am (local time).

Around 70 homes and other buildings were destroyed and more than 550 residents evacuated to facilities that included an ice-skating arena and a school gym.

There were no immediate reports of deaths. Officials said at least one resident and two firefighters sustained second-degree burns.

The Korea Forest Service said firefighters extinguished the blaze as of 4:30pm, helped by rain that began in the afternoon.

Their efforts were initially slowed by powerful winds that made it difficult to fly water-dropping aircraft, but officials managed to deploy helicopters in the afternoon.

The Korea Meteorological Administration said winds in the Gangneung area were blowing at 103 kilometres per hour. The strong winds also forced railroad operators to cancel at least a dozen passenger trains between Gangneung and other eastern coastal cities like Donghae and Samcheok.

The fire covered more than 379 hectares.

Firefighters during the earlier part of their response focused on establishing barriers to prevent the flames from spreading to more populated areas of Gangneung.

Photos showed firefighters spraying water toward burning homes and buildings and large, orange flames engulfing a pine forest near a seaside resort hotel.

The Korea Forest Service said that the fire was likely sparked by a tree that fell over a powerline after being snapped by strong winds.

AP