The statement is the latest development of an issue that emerged in 2017, when 47 NGOs published an open letter to the International Olympic Committee claiming there was increasing evidence that Tokyo 2020 was using timber supplied by companies associated with illegal logging and human rights abuses.

The Rainforest Action Network, one of the seven environmental NGOS involved in the most recent statement, then produced a report in November 2018 alleging that at least 134,400 sheets of tropical plywood from Malaysian and Indonesian rainforests have been used in the construction of Tokyo 2020 Olympic venues.

The Tokyo 2020's Sustainable Sourcing Code warned that organisers must only "use raw materials collected or cultivated in consideration of resource conservation including the perspective of mitigating deforestation and forest degradation".

Tokyo 2020 organisers have since revised their timber sourcing policy, but NGOs have claimed that this has not ended the use of timber associated with human rights abuses and rainforest destruction, saying that they are "deeply disappointed" by this.

"Regrettably, the new policy announced on January 18th of this year makes minimal improvements and fails to ensure the sustainability or even legality of the timber being procured," the statement continued. 

"By allowing Tokyo 2020 suppliers to continue sourcing high-risk timber from controversial companies, without meaningful due diligence, the Olympics will be leaving a bitter legacy for Japan.

"We call on all Tokyo 2020 organisers to:

"1) promptly disclose a detailed assessment of how sustainability and legality has been assured for all tropical timber products that have been procured to date; 

"2) immediately end the use of all wood products from the tropics or other high risk areas for Olympic construction unless full traceability to the area of harvest is established and compliance with the timber sourcing policy’s five criteria for legality, sustainability and rights, along with FPIC, are third party verified; 

"And 3) publish a thorough explanation of how the revised sourcing policy will make a difference in Tokyo 2020’s assurance of legality and sustainability throughout its supply chain, particularly with respect to high-risk timber."

"With the support of a working group of experts, we discussed revisions to the timber sourcing code with various stakeholders, including NGOs, and summarized the results of these discussions," responded Tokyo 2020 spokesman Masa Takaya, as reported by Reuters. 

"Tokyo 2020 is making maximum efforts to step up activities to help realize a sustainable society through the Tokyo 2020 Games and become a model for addressing sustainability issues both in Japan and other countries."

"Applying sustainability criteria to the supply of timber and plywood panels used for concrete construction purposes is a very new approach in Japan, so we believe the Tokyo 2020 Games will help increase the sustainability of timber supplied here."

The seven NGOs to release the statement were the Rainforest Action Network, Japan Tropical Forest Action Network Bruno Manser Fund, Environmental Investigation Agency Hutang Group, Sarawak Dayak Iban Association, TuK Indonesia, Walhi North Maluku and the Sarawak Campaign Committee. 

Tokyo 2020 is aiming to deliver a sustainable Games through its sustainability plan and its guiding principle, "Be better, together - for the planet and the people".

Initiatives include using the metal from recycled electronic devices to make Olympic medals and recycled aluminium from temporary housing in Fukushima to make Olympic torches.