By Hyunsu Yim

BUAN, South Korea (Reuters) -South Korea on Tuesday started evacuating thousands of teenage participants at the World Scout Jamboree from a campsite in the southwest of the country to safer areas mainly around the capital Seoul ahead of an approaching typhoon.

The evacuation is the latest blow to the 10-day jamboree, after hundreds fell ill due to a heatwave and amid mounting complaints from parents over its organisation, which prompted the earlier withdrawal of the U.S. and British scout contingents.

Typhoon Khanun, which has already wreaked havoc in southern Japan, is expected to hit southern areas of South Korea on Thursday before tracking up the peninsula, bringing strong winds and rain, according to weather forecasters.

At the sprawling campsite on reclaimed land, scouts were dismantling tents and folding up ground sheets on Tuesday, before carrying their laden backpacks to board nearby buses.

More than 1,000 buses were being deployed to move the 36,000 scouts remaining at the campsite from more than 150 countries, according to officials.

The convoys will be escorted by police helicopters and patrol cars, Interior Minister Lee Sang-min told a briefing. Seoul and its surrounding province of Gyeonggi would host more than 16,000 scouts, with others fanning out to six other areas of South Korea, he said.

"Each local government will check the cleanliness of the accommodations and toilets," the minister said.

His remark came after the head of UK Scouts told Reuters that poor sanitation was one of the reasons why the biggest contingent decided to leave the campsite early.

The organisers said most participants will have their own room or share with one other person.

"This is the first time in more than 100 years of World Scout Jamborees that we have had to face such compounded challenges," Ahmad Alhendawi, Secretary General of the World Organization of the Scout Movement, said in a statement.

President Yoon Suk Yeol on Monday ordered an emergency response team to implement the latest plans without a glitch.

Poland is due to host the next World Scout Jamboree in 2027, but President Andrzej Duda cancelled plans to visit the event in South Korea this week due to the typhoon, an official at the Polish Embassy in Seoul said.

The ill-fated jamboree has marred South Korea's successful track record hosting major events including the summer and winter Olympic Games and jointly hosting the soccer World Cup with Japan. The port city of Busan is currently bidding to host the Expo in 2030.

The jamboree is officially due to run until Aug. 12 and the South Korean government has insisted it will continue, with alternative programmes and a K-pop show.

(Reporting by Hyunsu Yim and Park Ju-min in Seoul and Hyun Young Yi in Buan; Editing by Ed Davies and Sonali Paul)