Tens of thousands of scouts were being evacuated from their problem-plagued South Korean campsite on Tuesday ahead of a typhoon, as the scout chief said the challenges were unprecedented in a century of global jamborees. 

"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.

He said the massive event, which brought together about 43,000 scouts to a campsite in South Korea's North Jeolla province, had been "very unlucky with the unprecedented heatwave and now the typhoon".

The adverse weather conditions had "significantly impacted the planning and delivery of the 25th World Scout Jamboree" he said, adding that despite the challenges, scouts had shown "true resilience, determination and leadership in the face of adversity".

The scout body said that it was the first time a campsite had been evacuated due to inclement weather since 1971, when a typhoon struck during a world scout jamboree in Japan.

At the sprawling campsite in Buan Tuesday, tens of thousands of scouts were packing up their tents and belongings and queuing up to get onto buses bound for alternative accommodation in Seoul and the surrounding areas.

Korea Special Forces were on hand to help with the evacuation, AFP reporters at the site saw. 

The government had said it would send 1,000 buses to move the mostly teenage scouts from the site.

- 'A really great time' -

Korean media have called the jamboree "a national disgrace" after an extreme heatwave caused hundreds of scouts to fall ill and prompted American and British scout groups to withdraw.

The scout chief acknowledged some shortfalls at the site, saying in a post on LinkedIn that they had a "bumpy start with... services and facilities". 

But scouts at the campsite told AFP they were sad to leave.

"It's really hard but we had a great time. It took some while to get used to the circumstances but the youth they had a really great time," Nicola Raunig, 27, Austria scout unit leader, told AFP. 

"I'm sad it will end now," she said, adding that she had hoped participants could have enjoyed "the whole experience".

"But we will make the best out of it," Raunig said.

Typhoon Khanun, which killed at least two people in Japan, is due to make landfall in South Korea on Thursday, near where the scouts were camping for their problem-plagued jamboree.

Organisers had insisted the event would continue despite the challenges, but on Monday they confirmed the scouts would be evacuated and the campsite closed due to the approaching typhoon.

South Korea's weather agency said Typhoon Khanun is forecast to bring heavy rain and strong winds across the Korean peninsula, including winds with a maximum speed of up to 44 metres (144 feet) per second -- powerful enough to derail a moving train.

Organisers have been strongly criticised by Korean media and parents of the scouts for a lack of planning for the extreme heat, even though South Korea had six years to prepare.

Media also reported on poor drainage at the site, rudimentary showers and toilets, and gruesome bug bites affecting the participants.

sh-kjk/ceb/aha