Organisers are preparing to evacuate tens of thousands of scouts from some 158 countries amid a typhoon warning.

The announcement on Monday came days after thousands of scouts left the jamboree site in southwestern Buan county due to a debilitating heatwave.

“The World Organization of the Scout Movement received confirmation this morning from the Government of the Republic of Korea that due to the expected impact of Typhoon Khanun, an early departure will be planned for all participants,” the body said in a statement.

“We urgently call on the Government to expedite the plan for departure and provide all necessary resources and support for participants during their stay and until they return to their home countries,” it added.

The Jamboree began on Wednesday with the participation of some 40,000 scouts from 158 countries. About 4,500 were from the United Kingdom, representing the largest national contingent, while about 1,000 were from the United States.

The British and American groups were among the first to withdraw at the weekend after hundreds of scouts fell ill due to extreme heat at the vast tree-less campsite.

The government and organisers sent in water trucks, air-conditioned spaces and medics in an effort to salvage the event. Various businesses also stepped in to help, donating tents, water and ice cream, while the Jogye Order of Korean Buddhism opened up its temples to the scouts.

But the new threat of the typhoon has forced more groups to leave the area.

The Australian scout group was the latest contingent to evacuate the campsite on Monday, according to the ABC broadcaster.

South Korea’s weather agency said the region will be affected by the storm as early as Wednesday.

President Yoon Suk-yeol’s office said he called for “contingency” plans, which could include relocating the scouts to hotels and other facilities in the country’s capital, Seoul, and nearby metropolitan areas.

Choi Chang-haeng, secretary-general of the jamboree’s organizing committee, said the group has secured more than 340 evacuation venues, including community centres and gyms, in regions near Buan.