British MPs voted unanimously on Wednesday for a motion declaring that Islamic State violence against ethnic and religious minorities in Syria and Iraq was genocide, and urging the government to do more to bring IS fighters to justice.
The government has held back from describing the violence carried out by the Sunni militant group against Yazidis, Christians and Shia Muslims in the Middle East as genocide, saying this was a question for an international court.
But the International Criminal Court (ICC) cannot make a judgment on whether violence amounts to genocide unless it is asked to do so, said MP Fiona Bruce, who proposed the motion.
"That is why supporting this motion is so important," she told parliament.
US Secretary of State John Kerry, the US House of Representatives, the European Parliament and the Parliamentary Assembly of the Council of Europe have all described the Islamist militant group's actions as genocide.
The parliamentary motion also called on the British government to ask the U.N. Security Council immediately to give the International Criminal Court (ICC) jurisdiction over the issue "so that perpetrators can be brought to justice".
"It is about doing justice and about seeing justice being done," Bruce said.
Recognition of genocide brings with it obligations on behalf of the international community to prevent, punish and protect people, she said. "Recognition of genocide ... is a crucial step."
The motion was passed unanimously, by 278 votes to zero.
IS has openly said it wants to eliminate the Yazidi religion, and has killed, raped and enslaved thousands of people from this and other minority groups.
The militants consider the Yazidis to be devil worshippers. The ancient Yazidi faith blends elements of Christianity, Zoroastrianism and Islam.
IS group enslaved an estimated 7,000 women and girls in 2014, mainly Yazidi women and children, and is still holding 3,500 as slaves, according to the United Nations.
The group has also attacked Christians and Shia Muslims in the region.
UK rights activists welcomed the parliamentary vote.
"It's hugely significant because the UK thus far has been unwilling to use the term genocide ... and it's starting to be a very lonely place being a country that's unwilling to use that term," Robert Clarke, legal counsel at religious rights group ADF International, told the Thomson Reuters Foundation.
"The UK should be taking a leading role in recognising the ongoing genocide in the Middle East in order to ultimately bring it to an end," Clarke added in a statement.
"We have an obligation to prevent and punish this 'crime above all crimes' under the 1948 Convention on Genocide. We cannot remain silent," he said.
Clarke said using the term genocide could deter young Europeans and Americans who are considering joining IS.
If the group is condemned universally as genocidal, and the international community is committed to justice for the victims and accountability for the offenders, "then we might be able to say we are doing all that we can to stem the flow of Brits and others to Iraq, to Syria," he said in an interview.
"What's going on here isn't just rape, or murder or kidnapping, or sexual slavery or forced sterilisation, as serious as all those things are," Clarke said.
"But it is those serious crimes being committed with an intention to eradicate a people based on their religion, their ethnicity. That's what makes it so serious," he added.