Thirty-six nations condemned Saudi Arabia on Thursday over the murder of journalist Jamal Khashoggi in a rare censure of the oil-rich kingdom at the UN Human Rights Council.

A statement read by Iceland on behalf of a group of states expressed "significant concerns" about reported abuses in Saudi Arabia and demanded justice following Khashoggi's killing.

"Investigations into the killing must be prompt, effective and thorough, independent and impartial, and transparent. Those responsible must be held to account," added the statement read by Iceland's UN ambassador Harald Aspelund.

It called on Saudi authorities "to disclose all information available" about its own investigation while cooperating with separate UN inquiries into Khashoggi's death.

The statement was backed by EU states along with Australia, Canada and New Zealand.

Human Rights Watch said the statement was "the first-ever collective action" at the council on rights in Saudi Arabia, which had successfully evaded criticism at the UN body.

HRW's Geneva director John Fisher called it "a landmark step toward justice" and urged "more scrutiny" of the country.

Khashoggi, a Washington Post contributor and critic of Crown Prince Mohammed bin Salman, was murdered at the Saudi consulate in Istanbul on October 2.

The UN special rapporteur on extrajudicial, summary or arbitrary executions, Agnes Callamard, is conducting an inquiry into the killing.

But Callamard is an independent human rights expert who does not speak for the UN and calls have mounted for Secretary-General Antonio Guterres to push for a full UN-backed probe.