Climate change is fuelling conflicts around the world and helping to drive the number of people forced out of their homes to new highs, the head of the UN's refugee agency said yesterday. After a few years of improvement, thanks mainly to large-scale resettlement in Afghanistan, the numbers of civilians uprooted by conflict is again rising. During 2007 the total jumped to 37.4 million, an increase of more than 3 million, according to statistics published today.

The figures, described as "unprecedented" by the UN, do not include people escaping natural disasters or poverty - only those fleeing conflict and persecution. But Antonio Guterres, the UN high commissioner for refugees, said that climate change could also uproot people by provoking conflicts over increasingly scarce resources, such as water.

In an interview with the Guardian, Guterres said: "Climate change is today one of the main drivers of forced displacement, both directly through impact on environment - not allowing people to live any more in the areas where they were traditionally living - and as a trigger of extreme poverty and conflict."

Guterres, who has held the post since 2005, said the number of refugees was likely to continue to increase for the foreseeable future. "More and more the international community will be facing an acceleration of people on the move for all kinds of reasons," he said.

As climate change, a global economic slowdown, conflict and persecution fuelled each other, it would be increasingly hard to categorise those on the run.

"What we are witnessing is a trend in the world where more and more people feel threatened by conflict, threatened by their own government, threatened by other political, religious ethnic or social groups, threatened by nature and nature's retaliation against human aggression - climate change is the example of that. And also threatened by ... a slowdown in global growth, plus structural change in energy and food markets," Guterres said.

The Portuguese diplomat is visiting London to launch a week of events marking World Refugee Day on Friday. Today a reproduction of a relief camp in the Darfur region will be erected in Trafalgar Square to raise awareness of the problem.

Guterres said funding from world governments had failed to keep up with the challenge of caring for refugees, describing it as "out of proportion with the dimension of the problem".

The task is also hindered by the legal distinction between refugees, who flee across borders and automatically become the UNHCR's responsibility, and internally displaced persons (IDPs), who flee their homes but remain in their home countries. In 2007 there were estimated to be 26 million of them, and only half receive direct or indirect help from the UNHCR. "They remain under the protection of their own governments, but the governments are sometimes part of the problem rather than solution," Guterres said.

He said the UNHCR was not seeking to widen its 1951 mandate, but wanted a review of the status of IDPs, to ensure they received more international help.

Statistics published today by the UNHCR show that nearly half the world's refugees are Afghan (about 3 million, mostly scattered in Pakistan and Iran), or Iraqi (2 million, largely in Syria and Jordan). The world's largest population of IDPs is in Colombia, where 3 million people have driven from their homes by years of insurgency and counter-insurgency. There are 2.4 million IDPs thought to be in Iraq, a rise of 600,000 over the past year. Almost all refugees end up in camps in their region, rather than in the west, which admits relatively few.

Guterres was critical of Britain's record, particularly on refugees from Iraq. Only 15% of their applications for refugee status have been granted, he said, and the UK's asylum system "still requires people to demonstrate that they are targets of violence and persecution, which is not always easy in situations of widespread violence." But he added: "At the same time it is true that the UK is not deporting people to central and southern Iraq."

© 2008 The Guardian