The UN's central emergency response fund faces a shortfall of $100m in 2011, with China and Italy among those accused of contributing too little

The international development secretary, Andrew Mitchell, is set to deliver a withering critique of the failure of some of the world's most economically developed countries to contribute to international disaster relief.

In a year in which 263 million people were affected by natural disasters – 110 million more than in 2004, the year of the Boxing Day tsunami in south-east Asia – Mitchell will say that lack of support from G20 countries risks undermining the world's ability to respond to future shocks.

His criticism comes amid evidence that, despite the Haitian earthquake and Pakistan floods this year, many governments are cutting back on donations to emergency relief funds, with the UN's disaster fund already facing a $100m shortfall.

It comes, too, as experts have been predicting that increasing incidences of floods, famines and other climate-related natural disasters could affect 375 million people every year by 2015, even if incidents such as earthquakes and conflicts are excluded.

Earlier this year, Mitchell set up an independent review of how the UK government responds to disasters. It is chaired by Lord Ashdown and led by an advisory board of humanitarian experts. At the heart of Mitchell's concern is the level of contributions to the UN's central emergency response fund, set up in 2005 in the aftermath of the Boxing Day tsunami and designed to speed up delivery of emergency funds.

The fund has given money to relief efforts for every major disaster this year, including many that did not make the news, such as locust infestation in Madagascar, lead poisoning in Nigeria and a measles outbreak in Lesotho. Many of these relief efforts are severely underfunded.

"It is vital that countries back the fund and make sure we are ready to help when it will be needed most," said Mitchell last week, adding he had felt it necessary to fly to the UN in New York to urge members to give more after the floods in Pakistan earlier this year. "Passing the hat around after the disaster has hit is not a satisfactory way of doing things."

Despite a UN general assembly resolution that it should be funded annually to the tune of $500m, a replenishment conference earlier this month saw only $358m raised, with China, the world's second-largest economy, pledging only $500,000 in 2011. Italy has been identified as another relatively poor contributor, promising only $1.5m.

By contrast, Britain, which has been the largest donor to the fund, ahead of the Netherlands and Sweden, will announce this week that it is giving £40m ($61.7m). Since the fund's foundation, Britain has given almost six times as much as Germany, more than twice as much as Spain and 14 times as much as the US.

As well as the shortfall in funding, Mitchell added that the recent experience showed that the UN still needed to improve its leadership and co-ordination on the ground, to avoid both delays and duplication of provision. Indeed, during the Haiti earthquake and the Pakistan floods this year, there was criticism that the international response was slow, and once it had begun there was poor co-ordination between humanitarian organisations.

Mitchell said: "2010 will be remembered as a dreadful year for humanitarian disasters. Even in difficult economic times, Britain can be proud that it stood by people in their hour of need. Sadly, the scale and intensity of disasters is predicted to increase.

"We must restock and replenish our response to emerging disasters and make sure the system is fit for purpose. The UN has a central role to play in this, but a lack of support for its disaster fund threatens to undermine its ability to deal with future shocks." Mitchell's department is one of only two – the other is the department of health – that has not seen its budget slashed by chancellor George Osborne in the current round of spending cuts. Instead, its funding will be increased until 2014.

How it spends its money, however, came under criticism last week from MPs concerned that it did not have enough resources adequately to monitor how its aid was spent.

In addition to supporting the central emergency response fund, Britain will give £19m to the UN High Commissioner for Refugees.

Refugees are the most one of the most vulnerable groups affected by conflicts and natural disasters. At the end of 2009 there were 43 million people displaced across the world as a result of conflict alone.

The £19m could help buy and deliver 118,000 lightweight tents in new emergencies, provide basic shelter for 14,500 displaced people or help 290,000 Afghan refugees to return home and restart their lives.