Children fleeing Islamic State as the battle for Mosul intensifies are finding sanctuary at a camp just 15 miles away.

Christian humanitarian agency World Vision has set up centres for the protection of child refugees at Zelican camp – a new settlement built to accommodate some of the up to one million people who are expected to flee Mosul in the coming days and weeks.

"Our child-friendly spaces provide a safe place for children to come to terms with the violence they've seen, and just take time to play as children again amidst the chaos of this conflict," said Aaron Moore, head of programmes for World Vision in Northern Iraq.

"We can only imagine the difficult journeys they've made and the horrors they've seen on the way. In most cases, they have nothing; they will be tired, hungry, thirsty and in need of food, water and somewhere to sleep. Our main concern at this point is the safe passage of children and their families out of Mosul and surrounding areas."

The Iraqi government announced the Mosul operation on October 17. Government troops backed by the US and other forces launched an air and ground offensive in the biggest operation since the Iraq invasion in 2003 and have since retaken around 50 villages and towns surrounding the city, which is ISIS' last stronghold in Iraq.

On Thursday, troops recaptured Bartella – a Christian town about nine miles from Mosul. On Saturday, the bells of the Mart Shmony Syriac Orthodox Church were rung for the first time since 2014.

Cardinal Vincent Nichols, Catholic Archbishop of Westminster, issued a statement on Monday offering his prayers to the people of Mosul who have been suffering "from the tyranny of Daesh [ISIS]".

"It is vital that protection of civilians, respect for humanitarian conventions and support for those fleeing their homes are at the forefront of this operation," he said.

"It will undoubtedly take time for the physical liberation to be realised. Only then can the hard work begin to establish the rule of law and rebuild the region's diverse social fabric of which the Christian community, many of whom I met in Irbil last year in the refugee camps offering them sanctuary from the violence, is an integral part. This rebuilding is a crucial step which will allow them and other refugees to return to their homes.

"My prayers are also with people from across the Middle East region suffering from the continuing violence."

World Vision is already supporting half a million people who fled Mosul when it was first occupied by ISIS two years ago. Spokesman Chris Weeks told Christian Today that the humanitarian situation is likely to get much worse before it can improve.

"Everyone is saying this could be the biggest humanitarian crisis of the year," he warned. "If you look at the numbers, up to a million expected to flee Mosul, this will rank as the largest crisis this year."

The agency is also providing clean water, hygiene kits, showers, toilets and basic household items such as cooking stoves to families displaced by the violence.