Iranian Deputy Foreign Minister Abbas Araqchi called on the United Nations on Tuesday to undertake reforms to reflect the "growing role of developing countries".
"To continue its presence in the international political and economic scene, the United Nations needs to undertake fundamental reforms," the ISNA news agency quoted Araqchi as saying.
He was speaking at a ceremony in Tehran to mark the 68th anniversary of the UN charter going into effect, which was attended by UN Development Programme administrator Helen Clark.
"These reforms must reflect the change in global order, particularly the growing role of developing countries, the right of nations to determine their own fates and to allow (nations) to enjoy new technologies," said Araqchi, whose country holds the presidency of the Non-Aligned Movement.
Araqchi led Iran's negotiating team in talks with the major powers last week on its controversial nuclear programme, which has drawn several rounds of UN sanctions as well as far tougher measures from the European Union and the United States.
Western governments suspect Iran is seeking to develop a nuclear weapons capability under the cover of its civilian programme, a claim vehemently denied by Tehran, which is pressing for an easing of the sanctions.
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"These illegal, inhumane and oppressive sanctions target Iranian citizens ... as well as the country's developing programmes in health, education and its fight against poverty," Araqchi said.
"Imposing such unfair sanctions against developing countries is not only contrary to the UN charter, but also exposes a serious threat to world peace and security," he said.
Tehran has struggled to obtain medical supplies because of sanctions, even though the health sector is not directly targeted by the international measures.
Clark told AFP on Tuesday that "sanctions either made by Security Council or unilateral should not harm humanitarian needs," but said that the World Health Organisation and the UN children's agency UNICEF had both offered to procure medicine to trade with Iran.
The UNDP administrator said Iran had made significant progress in health and eduction since 1990, but warned that the country faces many challenges, particularly the divide between rich and poor.
"Inequalities are quite high in Iran and over time, inequality becomes quite corrosive," Clark said of the country, where 55 percent of the population is under 30.
"Iran has the opportunity of a tremendous demographic dividend with a large youth population. Level of education is quite significant but if the youth don't see hope, don't see jobs, this dividend does not get realised".