The world doesn't need another Rwanda

They have lost their houses, their neighbourhoods and, in many cases, their loved ones.

Up to a quarter of Syria's population has been uprooted from their homes.

Already it is "the biggest refugee crisis of this century" and the "biggest displacement crisis of all time", says the United Nations, adding it is "nothing less than alarming".

And now, finally, the UN has admitted it.

The refugee crisis currently flowing out of Syria "is the worst refugee crisis since the Rwandan genocide almost 20 years ago".

Syrians flow over the Iraq border Picture: UNHCR.

The UN refugee agency, UNHCR, says the number of Syrians who have fled their homes has risen to 6.25 million, the largest refugee group of any country in the world and the "biggest displacement of all time".

UNHCR says one person escapes across Syria's borders every 15 seconds and approximately half of those displaced are children.

UN High Commissioner for Refugees, António Guterres, said displacement of Syrians was "unparalleled in recent history".

"Syria has become the great tragedy of this century - a disgraceful humanitarian calamity with suffering and displacement unparalleled in recent history," he said.

The outflow of Syrians has intensified in the past week, following news of a possible US military intervention.

Al Za'atri camp in Jordan is experiencing water shortages, disease and a crime wave. Picture

Refugee camps the size of cities are springing up in what were once just fields in the neighbouring countries bearing the brunt of the Syrian influx.

The Al Za'atri refugee camp near the Syrian border is now Jordan's fourth largest city and UN data suggests the Syrian refugee population currently stands at 716,000 in Lebanon, 515,000 in Jordan, 460,000 in Turkey, 168,000 in Iraq and 110,000 in Egypt.

With the threat of US air strikes and revenge chemical weapons attacks by rebel forces on the Syrian government, these numbers are likely to grow, placing incredible pressure upon the economies and resources of the host countries.

The UNHCR said these countries are carrying an "overwhelming burden" and have started placing various restrictions on entry.

There is increasing domestic frustration at the economic, political, security, infrastructural and social repercussions of this colossal influx, UNHCR said.