A group of 40 trees were planted to mark the four decades since the first outdoor World Championships in Helsinki in 1983.

School pupils were involved and had the chance to try out a forest running circuit with Balázs Baji, a world bronze medallist in the 110 metres hurdles at London in 2017 and who is now an ambassador for Budapest 2023.

"The World Championships are not just about the nine-day competition, but also about the positive legacy the event leaves behind," said Balázs Németh, the Budapest 2023 chief executive. 

"To this end, we are implementing our comprehensive sustainability programme, which focuses on mobilising the country's population, developing urban green spaces, public transport, waste management and raising awareness of environmental issues."

Jon Ridgeon, the chief executive of World Athletics, attended the planting and praised the sustainability efforts.

"Both World Athletics and the local Organising Committee are committed to leaving a sustainable and positive legacy for the future of the World Championships in Budapest," he said.

"This tree planting is a significant event for the local community."

This year's World Championships are due to take place between August 19 and 27 at the National Athletics Centre, a brand new 36,000-capacity stadium.

The venue has sustainability at its heart as it has been built by the River Danube on a site that needed to be completely rehabilitated due to contamination after industrial activity.

After the Championships, capacity will reduce to 14,000 and the surroundings will turn into a public park in 2024.

More than 500 trees and 2,000 shrubs have already been planted at the site, including 40 close to the stadium.

Thousands more trees are set to be planted in Budapest as part of a greening programme, in cooperation with a forestry company.

Other sustainability initiatives include the reduction of plastic bottles through the use of water balloons, drinking fountains and re-usable bottles.

Fans will be encouraged to walk to the stadium along the river while there will be reduced fares for public transport.

"The project will prioritise local, domestic partners to achieve national economic and environmental goals by reducing carbon emissions and transport costs," Budapest 2023 said.

"Making the event accessible and affordable for all is a crucial component of the World Athletics Championships' commitment to social responsibility. 

"Compared to other global events, ticket and package prices are affordable, with an additional 50 per cent discount for those who are active in sports through the World Championships Supporters' Club. 

"The Organising Committee is also encouraging more schoolchildren to participate in the World Championships through its Schoolhero programme, and has launched several initiatives to offer discounted tickets to civic groups, workplace communities and disadvantaged groups."