British lawmakers voted Wednesday to urge the government to recognize the Islamic State jihadist group's attacks on minorities in Iraq and Syria as genocide.
Members of parliament unanimously approved the motion – which is not binding on the government – by 278 votes to zero.
The vote in the 650-seat lower House of Commons calls on ministers to accept formally that ISIS's actions against Christian, Yazidi and other religious and ethnic minorities in Syria and Iraq constitute genocide.
But Foreign Office junior minister Tobias Ellwood, who has specific responsibility for the Middle East, said it was up to the courts rather than the government to make such a judgement.
"I believe genocide has taken place, but as the prime minister (David Cameron) has said, genocide is a matter of legal rather than political opinion," Ellwood said.
MPs from all parties urged Britain to use its position as one of the five permanent members of the United Nations Security Council to get the situation referred to the International Criminal Court.
Ellwood said any referral to the ICC by the UNSC "will only be possible with a united council and ideally with the cooperation of countries in which alleged crimes have been committed.
"But I draw the house's attention when efforts were made to refer the situation in Syria to the ICC in 2014 it was vetoed by Russia and China and we expect any Security Council resolution seeking to refer the situations in Iraq or Syria to the ICC against these countries could very well be blocked again.
"But further discussions are taking place. We are now in a different place than in 2014."
He added: "It is not for governments to be the prosecutor, the judge or indeed the jury."
The United States declared last month that Islamic State's slaughter of Christians, Yazidis and Shiites in Iraq and Syria amounts to a genocide and vowed to halt it.
Secretary of State John Kerry's "moral statement" did not place the United States under any new legal obligations, but the White House said it could back an international investigation by the ICC – which the United States is not party to – into alleged genocide.
The Islamic State group recruits Sunni extremists and has regularly carried out mass killings of Shiite Muslim, Christian and Yazidi prisoners.
AFP contributed this report.