The UK government on Tuesday officially acknowledged that the ISIS group committed "acts of genocide" against the Yazidi people in 2014.
The Yazidis where target of ISIS extremists and were subjected to massacres, forced marriages and sex slavery during the militants' 2014-15 rule in the northern Iraq province of Sinjar, the Yazidis' traditional home.
The UK foreign office made the announcement ahead of events to mark "the nine year anniversary of atrocities" committed by ISIS against the Kurdish-speaking Yazidi minority in Iraq.
"The UK has today formally acknowledged that acts of genocide were committed against the Yazidi people by ISIS in 2014," the statement said.
So far, the UK has acknowledged only four other instances where genocide has occurred, the Holocaust, Rwanda, Srebrenica, and acts of genocide in Cambodia.
"The Yazidi population suffered immensely at the hands of ISIS nine years ago and the repercussions are still felt to this day," UK's Middle East minister Tariq Ahmad said in the statement.
"Justice and accountability are key for those whose lives have been devastated," he added.
Murad Ismael, co-founder of global Yazidi organization Yazda, hailed the UK recognition as an "important step".
"Acknowledgement is the heart of justice process and helping victims to heal from the deep wounds of this genocide," he told AFP.
"I am pleased that the UK government has formally recognized the horrors suffered by the Yazidis as genocide", said Nadia Murad, a Yazidi Nobel Peace Prize Laureate campaigning against the use of sexual violence in war, particularly against the Yazidis.
"I hope that the British government will now begin to seek justice for the victims by holding British-born fighters to account," she added.
"The world cannot afford to let ISIS members walk free. It sends a message to the world that you can murder and rape with impunity."
The UK's lower house of parliament, the House of Commons, had unanimously voted to condemn the ISIS's treatment of Yazidis and Christians in Iraq as amounting to genocide in 2016, in a rare instance of parliamentary determination of genocide.
The foreign ministry had refused to acknowledge the genocide then, in keeping with a long-standing policy on the determination of genocide by courts rather than governments.
Nearly six years since Iraq declared "victory" over ISIS, many Yazidis have still not been able to return to Sinjar.
Thousands still live in precarious conditions in camps for displaced people.
Those who have returned face an unstable security situation and inadequate or nonexistent public services.
