By MATTHEW HICKLEY, Daily Mail

Last updated at 10:38 30 May 2006

England is the fourth most crowded country on the planet, with more people crammed into each square mile than China, India or Japan, a startling report reveals.

Experts warn that mass migration is causing serious environmental harm around the world.

It is especially putting pressure on densely populated states such as Britain, threatening resources such as water supplies.

The research by the Optimum Population Trust think-tank claims that although the UK has a moral obligation to shelter genuine refugees, it needs large-scale immigration 'like a hole in the head'.

It warns that governments across the world have focused on the economic impact of mass migration.

But they have failed to grasp the potentially massive environmental costs as swathes of land are exhausted and abandoned in a 'scorched earth policy on a global scale'.

The answer, the think-tank says, is to encourage families to stay in their own countries through sustainable development.

Since Labour came to power, record levels of immigration have added 1.2million to Britain's population, which topped 60million last year, including just over 50million in England.

That means England ranks fourth in the world for population density - excluding small island or city states such as Singapore or Monaco.

Only Bangladesh, South Korea and the Netherlands are more crowded. The French have more than three times as much land per person.

An estimated 300,000 immigrants arrive here each year, but ministers insist huge numbers are needed to fill gaps in the economy, and are introducing a points system to attract more skilled foreigners.

According to the Optimum Population Trust report, to be submitted as evidence to a Parliamentary inquiry on population, Britain's projected population growth of more than ten million by 2074 is equivalent to building 57 more towns the size of Luton.

Resource and energy shortages

With parts of the country already facing serious water supply problems, population growth will make the UK increasingly vulnerable to resource and energy shortages while increasing its contribution to climate change, the study warns.

Professor Aubrey Manning, of Edinburgh University - patron of the think-tank - said: 'The UK has a moral obligation to accept some immigration, given the current world situation, but we need immigration like we need a hole in the head.'

The Earth's life-support systems are 'clearly under severe pressure,' he said, with mass immigration often caused by rapid population growth which outstrips a region's ability to support it. This leads to land becoming degraded.

The study cites UN figures showing that number of migrants worldwide rose by 17million a year from 2000 to 2005, reaching an estimated 192million last year.

There are around 30million environmental refugees, with a further 135million worldwide at risk from the spread of deserts, according to the UN. The answer must be to prevent or cure the environmental damage of soil erosion and advancing deserts, the report warns, rather than mass migration to escape it.

The report also warns that rising populations and migration are together hampering attempts to achieve the UN Millennium Development Goals, designed to tackle poverty, disease and deprivation in the developing world.