SEOUL, South Korea (AP) — South Korea is plowing ahead with the World Scout Jamboree, rejecting a call by the world scouting body to cut the event short as a punishing heat wave caused thousands of British and U.S. scouts to begin leaving the coastal campsite Saturday.

Hundreds of participants have been treated for heat-related ailments since the jamboree began Wednesday at the coastal site in Buan as South Korea grapples with one of its hottest summers in years.

Prime Minister Han Duck-soo said during a news conference that South Korea is determined to continue the event as planned through Aug. 12. He promised additional safety measures including more medical staff, air-conditioned vehicles and structures that provide shade.

South Korean President Yoon Suk Yeol promised an “unlimited supply” of air-conditioned buses and refrigerator trucks to provide chilled water.

Around 700 additional workers will be deployed to help maintain bathrooms and showers, which some participants have described as filthy or unkempt. There also will be more cultural activities involving travel to other regions so scouts aren’t entirely stuck at a venue with heat problems, officials said.

About 40,000 scouts from 158 countries, mostly teenagers, are at the jamboree campsite built on land reclaimed from the sea. Long before the event’s start, critics raised concerns about bringing that many young people to a vast, treeless area lacking protection from the summer heat.

Han insisted organizers made “significant improvements” to address the extreme heat and said the decision to continue was supported by representatives of national scout contingents who met Saturday.

Han stressed how the country was pouring national resources into the event, including dozens of government vehicles providing cooling systems, shade structures procured from military bases and teams of nurses and doctors from major hospitals.

“We will continue to try until the participants are fully satisfied,” Han said.

The World Organization of the Scout Movement previously asked South Korean organizers to consider ending the event early. Organizers need to provide assurances there will be additional resources going forward to address issues caused by the heat wave, the organization said in a statement.

“We continue to call on the host and the Korean government to honor their commitments to mobilize additional financial and human resources, and to make the health and safety of the participants their top priority,” the statement said.

The U.K. Scout Association announced it was pulling out more than 4,000 British scouts and moving them to hotels. Hundreds of U.S. scouts also were expected to depart the site over the weekend and relocate to a U.S. military base near the capital, Seoul. An email from the U.S. contingent said leaving was necessary because of the extreme weather and resulting conditions.

The U.S. Embassy did not immediately respond to questions about accommodations for the scouts at Camp Humphreys. But the South Korean organizing committee confirmed the U.S. was among the national contingents intending to leave, also naming Singapore.

Some scouts and family members expressed disappointment. Raymond Wong, a San Francisco Bay Area engineer whose sons are attending, said participants should be able to choose if they leave.

“They are doing just fine and having a lot of fun. They are very upset about the news,” Wong said of his sons, ages 14 and 16.

South Korea this week raised its hot weather warning to the highest level for the first time in four years, with temperatures around the country hovering between 35 and 38 degrees Celsius (95 and 100 degrees Fahrenheit) on Friday. At least 19 people have died from heat-related illnesses since May 20, the Ministry of the Interior and Safety reported.

The government said 138 jamboree participants received treatment for heat-related illnesses Thursday. At least 108 participants were treated for similar ailments following Wednesday’s opening ceremony.

Choi Chang-haeng, secretary-general of the jamboree’s organizing committee, insisted the event is safe enough to continue. He linked the large number of patients Wednesday to a K-pop performance during the opening ceremony, which he said left many teens “exhausted after actively releasing their energy.”