The UN said on Friday it was in talks with Iran over $16.3 million in overdue fees, which Tehran says have become impossible to pay due to US sanctions.
Iran and the Central African Republic have lost their voting rights in the 193-member UN General Assembly because they are in arrears on contributions to the world body’s operating budget.
“It's not from lack of willingness of the Iranians to pay or no lack of willingness for us to engage with them in finding a solution to this issue,” UN spokesman Stephane Dujarric told reporters on Friday.
“Iran is a subject of bilateral sanctions, which impacts its ability for banking, and the UN's accounts are in the United States, in New York.
"And so we have to find a way around the problem.”
Iran's Foreign Minister Javad Zarif used social media to condemn his country's loss of voting rights, which came into effect in January.
Iran has been unable to pay the UN due to US sanctions that were imposed after former president Donald Trump withdrew from the nuclear deal in 2018, said Mr Zarif.
“Iran’s inability to fulfil its financial obligation towards the United Nations is directly caused by unlawful unilateral sanctions imposed by the United States,” Mr Zarif wrote in a letter to the UN, which he posted on Twitter.
US President Joe Biden has said he is willing to lift sanctions on Iran if it comes into compliance with the 2015 nuclear deal, but talks that began in early April in Vienna have yet to result in an agreement.
Three other African countries – Comoros, Sao Tome and Principe, and Somalia – also owe the UN money. But they can still vote in the current session, which ends in September, thanks to an assembly resolution.
UN members whose arrears equal or exceed the sum of their contributions for the preceding two full years lose their voting rights, according to the UN Charter.
Allowances can be made for situations beyond a UN member's control.
According to a letter from UN Secretary General Antonio Guterres, the minimum payments needed to restore voting rights are $16,251,298 for Iran and $29,395 for the Central African Republic.