"The costs of delaying action will increase rapidly over time...

"By 2050, 4.2 billion people (over 45 percent of the global total) will be living in countries that cannot meet the daily requirement of 50 litres of water per person to meet basic needs."

The population, which has doubled to 6.1 billion in the past 40 years, is projected to surge 50 percent to 9.3 billion within another half century - with all the growth in developing countries whose resources are already overstretched.

The report said water was being used and polluted at catastrophic rates.

WATER CONSUMPTION SURGES

At present 54 percent of available fresh water supplies are being used annually - two-thirds for agriculture.

This figure is set to surge to 70 percent by 2025 due to population growth alone, and 90 percent if consumption in the developing countries reached the levels in the developed world.

Water is already being used at unsustainable rates in many countries, with water tables under some Chinese, Latin American and South Asian cities dropping by more than one metre a year and water from seas and rivers being diverted with occasionally disastrous results.

The report said 1.1 billion people already did not have access to clean water, and in developing nations up to 95 percent of sewage and 70 percent of industrial waste was simply being dumped untreated into water courses.

Vital rain forests are being destroyed at the highest rate in history, taking with them crucial sources of biodiversity and contributing to climate warming, thereby boosting already rising sea levels.

SEAS OVEREXPLOITED

The seas continue to be massively overexploited and erosion is taking a rising toll of plant species - one quarter of which could be lost forever by 2025.

The United Nations said food production would have to double and distribution would have to improve to feed the exploding population, with most of the increase coming from higher yielding varieties which needed more environmentally dangerous chemicals to grow.

It said the globalisation of commerce had increased global wealth but at the same time added to global inequalities, with the hordes of the world's forgotten poor forced to plunder their scarce natural resources simply to survive from day to day.

The global HIV/AIDS epidemic had spiralled out of control and far too little money was being made available to stem it and treat it and its related tide or orphans and outcasts.

A crucial key lay in giving women - who played a major and largely unsung role in rural communities across the globe - a far greater say in society and, equally importantly, in setting the size of their desired families.