Thousands of scouts at an international event in South Korea are being evacuated from a campsite due to an incoming tropical storm.
Several countries including the UK had already left, blaming high temperatures and poor sanitary conditions at the camp.
UK Scouts chief executive Matt Hyde said he felt let down by organisers and UK activities had been set back years.
The site had become a health risk, he told the BBC.
Attended by more than 40,000 young people, the World Scout Jamboree has been plagued by problems from the very start.
Hundreds had fallen ill amid 35C (95F) heat, with scouts from the UK among those affected by heat exhaustion.
The British group of 4,500 people, the largest in attendance, arrived at the campsite in Saemangeum near the town of Buan last week but were transferred to hotels in the capital Seoul on Saturday.
Mr Hyde said the relocation will cost the UK Scout Association well over £1m from its reserves.
“We had commitments to those reserves that will of course mean that we can’t now do things that we wanted to do over the next three to five years,” he said.
The US and Singapore have also already pulled their teams from the campsite.
World Scout Jamboree organisers said on Monday that the South Korean government told them it was no longer safe to hold the event.
The government said it had listened to the concerns of the World Organisation for Scout Movements and national delegations, who had been requesting they close the site for days.
Some 36,000 people in Saemangeum will be taken by bus to areas which are not in the path of the storm, South Korea’s Vice Minister for Disaster and Safety Management, Kim Sung-Ho, has said.
The event “is still continuing,” but “the location is only changing because of the natural disaster,” he added.
Officials are seeking alternative venues and accommodation in and around Seoul.
The evacuation will begin on Tuesday at 10:00 local time (01:00 GMT).
Severe Tropical Storm Khanun, which has already forced evacuations and cut off power to thousands in Japan, is forecast to reach South Korea’s southern Jeolla province on Thursday.
Originally classified as a typhoon, the weather system has weakened but is still bringing high winds and torrential rain to the region.
Heatwaves have become more frequent, more intense, and last longer because of human-induced climate change.
The impact of climate change on the frequency of storms is unclear but increased sea surface temperatures mean they are likely to be more intense and bring more extreme rainfall.