UNITED NATIONS (Reuters) - The United Nations Security Council on Thursday approved the creation of a U.N. investigative team to collect, preserve and store evidence in Iraq of acts by Islamic State that may be war crimes, crimes against humanity or genocide.

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The 15-member council unanimously adopted a British-drafted resolution, after a year of negotiations with Iraq, that asks Secretary-General Antonio Guterres to establish a team “to support domestic efforts” to hold the militants accountable.

British Minister of State for the Middle East Alistair Burt said Britain would provide some $1.3 million to help establish the team.

“There can never be adequate recompense for those who were forced to endure the wanton brutality of (Islamic State) and the dead will not be brought back, but this resolution means that the international community is united in our belief that there should, at least, be accountability,” Burt told the council.

Use of the evidence collected by the team in other venues, such as international courts, would “be determined in agreement with the Government of Iraq on a case-by-case basis.” Evidence is for primary use by Iraqi authorities, followed by “competent national-level courts,” according to the resolution.

Thousands of foreigners have fought with Islamic State and some are already being prosecuted when they return home.

U.N. experts said in June last year that Islamic State was committing genocide against the Yazidis in Syria and Iraq to destroy the minority religious community through killings, sexual slavery and other crimes.

International human rights lawyer Amal Clooney and Nadia Murad, a young Yazidi woman who was enslaved and raped by Islamic State fighters in Mosul, have long pushed Iraq to allow U.N. investigators to help.

Clooney and Murad, who were both in the Security Council for Thursday’s vote, described the resolution as a milestone in the fight for justice. “Nadia and I exchanged a warm smile when we saw the 15 hands go up in the chamber,” Clooney told Reuters.

“It’s been a long time coming; in the meantime, evidence has been lost and we’ve lost some opportunities along the way, but the fact that we have this resolution now means that justice is finally possible,” she said.

Murad said she was “very happy” the council had acted.

The Security Council met during the annual gathering of world leaders for the U.N. General Assembly.

“We look ahead to the next steps and it’s really the next steps that will define whether this piece of paper we acquired today will become real justice on the ground for Yazidis and other victims of ISIS,” Clooney said.

Iraq’s foreign minister Ibrahim al-Jaafari officially requested international help in a letter to the Security Council last month. The council could have established an inquiry without Iraq’s consent, but Britain wanted Iraq’s approval.

Islamic State’s self-proclaimed caliphate effectively collapsed in July, when U.S.-backed Iraqi forces completed the recapture of Mosul, the militants’ capital in northern Iraq, after a nine-month campaign.