As the West prepares to celebrate Christmas, millions of suffering Iraqis and Syrians are in danger of being forgotten, according to the head of a leading charity that works in the region.

The turmoil in the Middle East has produced the worst refugee crisis in modern times but in spite of the huge numbers involved, the West is in danger of forgetting all about them.

The deaths of two Syrian babies from cold last week was an example of the conditions faced by hundreds of thousands on a daily basis. The babies were born in the rugged outskirts of the Lebanese border town of Arsal, where many thousands of Syrians are living in unheated tents in freezing temperatures.

Jeremy Moodey, chief executive of Embrace the Middle East, said: "The Reuters news agency suggests that the number of displaced Syrians and Iraqis is now equivalent to the population of London. In fact, it is much worse. Greater London has a population of just over eight million. A closer analogy would be the combined populations of England's three biggest urban areas – London, Birmingham and Manchester."

Embrace the Middle East, a Christian charity tackling poverty and injustice in the Middle East, has just launched its Christmas appeal to provide food, healthcare and education to refugees of all faiths and backgrounds trying to rebuild shattered homes and lives.

Mr Moodey added: "It is easy to forget that the terrible violence in Gaza over the summer is ultimately a refugee problem.

"As many as two-thirds of the 1.8 million Palestinians in Gaza are actually refugees whose forebears fled there from other parts of Israel/Palestine in 1948-49 after the creation of the State of Israel."

However, in spite of "desperate situation" for 20 million refugees struggling to survive in the Middle East today, there are signs of hope, he said.

"The region's small Christian communities are responding to the needs of refugees with a generosity of spirit and an abundance of compassion which is humbling, especially when one considers all the other pressures on Middle East Christians," he said.

Communities working to help include the Anglican diocese's Refuge Egypt project in Cairo, the Middle East Council of Churches' work among refugees in Gaza and the West Bank and the assistance offered by Lebanese Baptists and Catholics to Syrian refugees.

When Mr Moodey first visited one of the Syrian refugee projects the charity supports in Lebanon's Bekaa valley two years ago, he wrote that "helplessness" was the word that came to mind. "You could see it in the refugees' vacant looks, in their almost palpable numbness. Whole lives had been turned upside down, futures destroyed, and hope was in short supply, especially as the Levant's harsh winter approached. The only respite for these desperate souls was the 'winterization packages' (blankets, mattresses, stoves) being handed out by our Lebanese Christian partners."

The head of the UNHCR's Middle East and North Africa bureau, Amin Awad, recently told journalists in Geneva that the onset of winter was a serious threat to the region's refugees. "I wish we could support everybody, and I wish that we could keep everybody warm", he said. About half of the UN's $3.7bn appeal for Syrian refugees in 2014 has been raised to date, with barely a month to go until the end of the year.

The World Food Programme said this month that it had been forced to cut rations to more than four million displaced Syrians after a financial shortfall which it described as "dire".