In an appeal for Member States to help, they said that financing their work adequately had been a concern for several years, and that the COVID-19 crisis had made their work even more difficult.
Today, Member States have only paid about 60 per cent of their commitments to the United Nations regular budget.
As a result, some experts are unable to carry out their mandates properly, the Special Procedures coordination committee said in a statement, describing rights experts as the "eyes and ears" of the Human Rights Council in Geneva.
Their work includes making country visits to engage State representatives and civil society, meeting victims of rights violations and making concrete recommendations to assist States in fulfilling their human rights obligations, they added.
The experts work on a voluntary basis; they are not UN staff and do not receive a salary. They are also independent from any government or organization.
The Human Rights Council's Special Procedures bodies include the 56 mandates that cover international human rights; these include violations of the rights of communities and populations historically subjected to discrimination.
In their appeal to Member States, the experts expressed serious concern that the lack of urgent action to address the funding crisis "may create a protection gap", as they endeavour to fulfil their obligations to report to UN bodies, continue their outreach to victims, and engage in ongoing urgent matters".
"As in every area of human rights, the COVID-19 pandemic must not be used as a justification for States to fail to fund the very mandates that they have chosen to establish," the Committee said.
"Moreover, the experts, who work as unpaid volunteers, have now incurred additional personal costs, including to ensure access to the Internet and essential technology, as well as for the care of children and other relatives, as they endeavor to fulfil their obligations to report to UN bodies, continue their outreach to victims, and engage in ongoing urgent matters.
"While Special Procedures mandate holders have gone above and beyond their normal duties to support victims of human rights violations, States cannot claim that they are adequately supporting them unless they fully comply with their financial commitments to the UN's regular budget", the Committee said.
The call by the Coordination Committee takes place while the Human Rights Council and the General Assembly are in session in Geneva and New York.
The Coordination Committee is urging participants at both events to heed members' call during these important deliberations, "and to take practical and urgent steps to address the UN financial crisis immediately", said the news release from the UN rights office, OHCHR.