While ministers have so far refused to be drawn into the debate about whether the attacks on Shia Muslims, Christians, Yazidis and other minority groups in the Middle East should be classified as genocide, there is a growing push from MPs and peers to take action through international legal institutions.
The group of UK peers, including the likes of former Lord Chancellor Lord Mackay, Lord Carlile, the former independent reviewer of terrorism legislation, and Baroness Butler-Sloss, the former president of the High Court Family Division, believe David Cameron should take a stand on the issue.
"We urge you to revisit this position for the sake of tens of thousands of Christians and other religious minorities who are currently subject to acts of genocide in the Middle East," head of the peers' group, Lord Alton wrote.
"As a signatory to the 1948 UN Convention on the Prevention and Punishment of the Crime of Genocide, the United Kingdom has an obligation under international law to 'prevent and punish' acts of genocide."
This development comes after the European Parliament earlier this month voted unanimously to classify the persecution of religious minorities in the Middle East as genocide.
UK Should Initiate Proceedings — Peers
However, the ICC could begin proceedings if the UN Security Council handed down an order to do so.
"Even if it is accepted that a recognition of genocide should only be made by the ‘international judicial system' — a position not shared by many of our European neighbors — the starting point for such action must come from the members of the UN Security Council, including the United Kingdom," the UK peers argued.
"In order for the international judicial system to play its part, Her Majesty's Government must first act," Lord Alton added.
"History is littered with examples where the international community failed to recognize atrocities while they were happening.
"We have been too slow to name the murderous campaign against religious minorities in Syria for what it is; too slow to listen to their pleas for help."