More than 1,000 vehicles are being used to move 37,000 scouts - mostly teenagers - from the World Scout Jamboree that opened last week in Buan, a county on South Korea's southwestern coast.

Most will be housed in Seoul, where officials have secured university dormitories, government and corporate training centres, and hotels.

Tropical Storm Khanun has swirled around Japan's southwestern islands for more than a week bringing a deluge of rain, knocking out power and damaging homes.

Early on Tuesday morning, the storm was centred 217 miles south of Kagoshima, a city on the southwestern tip of Japan's main southern island of Kyushu.

Khanun had winds of 67 mph with gusts to 89 mph and was moving slowly north, the Japan Meteorological Agency said.

South Korea's weather agency, which measured the storm at typhoon strength of 78 mph, expected it to increase in power before making landfall on the Korean Peninsula on Thursday morning.

Evacuating the scouts from the coastal campsite is expected to take six hours or more.

The Jamboree attended by scouts from 158 countries started last Wednesday at the site on land reclaimed from the sea.

Hundreds of participants have already been treated for heat-related ailments during one of South Korea's hottest summers in years.

Concerns had been raised beforehand about having such vast numbers in the expansive treeless area lacking protection from the summer heat.

Organisers have said the campsite will not be used for any event after the scouts leave.

The evacuations were announced after the World Organisation of the Scout Movement called on South Korea to quickly move the scouts from the storm's path and provide necessary resources for participants until they return to their home countries.

Read more:
British Scouts move into Seoul hotels after heatwave hits World Jamboree
4,000 UK Scouts to be moved into hotels as heatwave hits World Jamboree

The hot temperatures have already forced thousands of British and American scouts to leave the site.

The British scouts - about 4,500 - were transferred to hotels in Seoul while the American scouts, numbering about 1,000, were moved to Camp Humphreys, a major US military base 45 miles south of the capital.

"This is the first time in more than 100 years of World Scout Jamborees that we have had to face such compounded challenges," said Ahmad Alhendawi, secretary general of the World Organisation of the Scout Movement.

"It's disappointing that these adverse weather conditions have forced us to shift our plans."