The UN Human Rights Council established a special investigator on Iran on Thursday, a move spearheaded by Washington that will subject Tehran's record to UN scrutiny for the first time in nearly a decade.

Activists welcomed the move as historic, underlining the need for a focused investigation into widespread allegations of abuse, including arrests of political opponents and torture.

The 47-member forum, overcoming Iran's objections to a resolution brought by Sweden and the US, approved it by 22 votes in favor, 7 against and 14 abstentions.

'What we've just witnessed is a real seminal moment for this body with the establishment of a special rapporteur on the human rights situation in Iran,' US Ambassador Eileen Chamberlain Donahoe told reporters.

'Today we've seen the Council able to respond to a chronic, severe human rights violator, which is Iran,' she said.

The lack of an investigator on Iran had been a 'glaring omission' at the Council, which has rapporteurs for countries with poor records including North Korea and Myanmar, she added.

This is the first special rapporteur on a specific country that the UN Human Rights Council has set up since its creation nearly five years ago.

Britain, France and the US were among those approving, joined by Brazil for the first time in years. China and Russia were among those rejecting the text.

In Washington, Tom Donilon, President Barack Obama's National Security Adviser, said the appointment reaffirmed 'the global consensus and alarm about the dismal state of human rights in Iran.'

The Human Rights Council voiced concern at Iran's crackdown on opposition figures and increased use of the death penalty, and called on the Islamic Republic to cooperate with the UN envoy to be named to the independent post.

UN officials and diplomats say Iran has not allowed UN human rights experts to visit since 2005, when hardliner Mahmoud Ahmadinejad was elected president, defeating the relatively moderate Mohammad Khatami.

Even if the new rapporteur is not allowed into Iran, he would still be expected to contact the government frequently about allegations and produce an annual report incorporating testimony from activists and alleged victims of abuse.

Iran, meanwhile, criticised the United Nations decision stating that it was a Washington ploy to put pressure on Tehran and showed US 'double standards' on the issue.

Tehran said the move was part of Washington's strategy of putting pressure on the Islamic Republic, which it has considered an enemy since the 1979 revolution that overthrew the western-backed Shah.

The United States and other world powers tightened sanctions on Iran over its disputed nuclear programme last year.

'The aim of the resolution was to put pressure on the Islamic Republic and to further sidetrack the UN Human Rights Council's periodic review of the human rights situation across the world,' Foreign Ministry spokesman Mehmanparast told the official IRNA news agency.-Reuters