Gordon Brown: While the world looks elsewhere, a nation is dying in silence

It now has a name: "the hunger season". The United Nations rapporteur on food has described what is going on as "silent mass murder".

And, almost unbelievably, the World Food Programme, through no fault of their own, have just had to make their "agonising" life-and-death decision to restrict food aid to children under two and to cut food aid for children over the age of two.

Why? Because one third of the funds they appealed for from rich countries have not been subscribed. Pakistan summons our urgent attention. But while floods have been destroying Pakistan, famine and floods have created an emergency in Niger.

Soon Niger will become the worst place on earth for maternal mortality, with one mother in every seven dying in childbirth. Already 1 in 6 children in Niger die before their fifth birthday, and even before the crisis 43 per cent of children were chronically malnourished.

With school attendance now falling fast it will become, in 2010, one of the countries where the least proportion of children go to school, and at the same time is among the countries with the poorest supply of doctors, nurses and midwives per head of population.

Talk of meeting the Millennium Development Goals sounds hollow when, on top of endemic poverty, Niger is witnessing some of the worst levels of famine and malnutrition we have seen. It has been doubly hit because bad crops last year have left people hungry and now rainfall this year has washed away stores of millet, sorghum and corn and washed away hope with it. Prices are so high for available food that people literally cannot afford to eat.

Today the "at risk" are 7 million of Niger's people – half their country's population. A world emergency in malnutrition is defined when 15 per cent of the population of children between three and five are suffering acute hunger and underfeeding. Already the figure in Niger is 16.7 per cent and in some areas 40 per cent. We know that in the last few months 127,000 children under five years old have been admitted to hospital for malnutrition-related problems. It is said by medical experts that almost half of malnourished children under two will not survive.

So – 50 years after their independence, with a coup this year reflecting continuing political instability – the people of Niger are in a worse position than at any time in their post-colonial history.

For months the United Nations Office for Co-ordinating Humanitarian Affairs (OCHA) and the World Food Programme – and NGOs – have been warning of a disaster in the making and working together to intensify their supply of aid. But they are $80m (£50m) short.

"We had planned to distribute 75,000 tonnes of food in August and September," reported the WFP deputy director in Niger, "but because of limited resources can only hand out 42,000". Now more than 212,500 tonnes of food are needed between August and December to fill the food gap.

But are these problem insoluble? No. Niger has long-running political, social and economic problems which must be dealt with systematically and comprehensively, but we can also act now to relieve the suffering of hungry children, and take immediate action to ensure better harvests next year and beyond.

I urge all countries to share the $80m or so shortfall (for Britain that would be less than $10m, America no more than $20m) and subscribe to the urgent food needs of the Niger population.

But what this shortfall shows – as does Pakistan's urgent needs – is that the UN Disaster Fund, Cerf, needs to be much bigger so that funds can always be mobilised immediately, without waiting to hand the begging bowl round.

As Save the Children have told us, £50 can support and treat a child with severe malnutrition through our treatment programmes, £155 can pay for a nurse for one month to care for severely malnourished children suffering from medical complications, and £5,000 can provide one month of clinical supplies such as intravenous fluid, disinfectant and soap for children who are dangerously malnourished.

From October onwards (after the harvest), post-harvest recovery projects need to be in place. We should extend the cash-for-work programme pioneered by the World Food Programme beyond the current 40,000 households. At the same time we must help to equip Niger for future harvests: sadly only 12 per cent of Niger's land is currently arable land. But irrigation and water schemes matched to agricultural development should be given more support to make the land productive.

There are no easy answers. But today where there is suffering without hope, we can prevent children dying painful, avoidable deaths.