Theresa May has spoken to the prime minister of Iraq about the battle against Islamic State (IS).
The pair are set to meet at the UN General Assembly in New York later this month where they will continue discussions about the fight against IS, also known as Daesh.
Mrs May praised Iraqi leader Haider al-Abadi for his "personal leadership" in the fight against the terrorists, but also raised "concerns" that some state-backed militias may have committed abuses.
It comes after the Iraqi government set up an investigation into alleged abuses against civilians during the military operation to retake Fallujah.
Human Rights Watch has said it has received "credible allegations of summary executions, beatings of unarmed men, enforced disappearances, and mutilation of corpses" around the outskirts of the city.
Summarising the phone call, a Downing Street spokeswoman said: "This morning the Prime Minister called prime minister Abadi of Iraq to discuss progress in countering Daesh and creating the right conditions for Iraq's stability and prosperity.
"The Prime Minister welcomed prime minister Abadi's personal leadership in the battle against Daesh, noted the progress made by Iraqi security forces and reaffirmed the UK's continued commitment to the military campaign.
"The leaders discussed next steps in the campaign, including the operation to retake Mosul, and agreed that alongside the military effort there needed to be governance, stabilisation and humanitarian elements.
"They agreed the UN General Assembly later this month would be a good opportunity for the Iraqi government to update the international community on the progress of the campaign."
She added: "The Prime Minister raised concerns over reports of abuses being committed by some elements of the state backed militias of the Popular Mobilisation Forces (PMF). The leaders agreed that it was important that forces liberating Daesh territory should be following due process.
"They looked forward to meeting at the UN General Assembly in New York."