According to the Optimum Population Trust, Britain's rising birth rate, currently growing at the highest rate for nearly 30 years, should be considered an environmental liability.

"Each new UK birth, through the inevitable resource consumption and pollution that UK affluence generates, is responsible for about 160 times as much climate-related environmental damage as a new birth in Ethiopia, or 35 times as much as a new birth in Bangladesh," the report says.

It calls on the government to introduce a "stop at two children" or "have one child less" guideline and to review incentives that may lead some teenage girls to become pregnant.

"A voluntary stop-at-two guideline should be adopted for couples in the UK who want to adopt greener lifestyles. It would aim to set an example," it says.

The author of the report, John Guillebaud, professor of family planning and reproductive health at University College, London, made the call after figures from the office of national statistics showed 669,531 babies were born in Britain last year, with the UK having the highest teenage pregnancy rate in western Europe.

While most of Britain's annual population rise of nearly 300,000 people is from immigration, only 21.9% of new births were last year to non-UK born mothers, says Prof Guillebaud. Each woman in England and Wales, he says, can now be expected to have 1.87 children, the highest total fertility rate for 26 years.

Unless action is taken the UK population will grow by a further 10 million by 2074, says the report.

"UK population has grown by 20% since 1950 - in less than a lifetime. There are more than 60 million people now living in the UK, one of the most densely populated countries in the world, and our numbers are rising faster than ever before.

"UK population is growing by the equivalent of a city larger than Cardiff every year."

Voluntary population stabilisation programmes have a proven record of success, says Prof Guillebaud. "A voluntary 'two-child' population policy in Iran, for example, succeeded in halving fertility in eight years, as fast a rate of decrease as that of China, whose much-criticised one-child policy began in 1980."

But Dr Guillebaud says the NHS must take much of the blame for not limiting unwanted teenage pregnancies. "This is ... related to the disastrous trend ... for primary care trusts to shut down community family planning clinics."

The report, which is published on world population day, says that the planet faces the biggest generation of young people in history - what it terms a "youthquake" - with major social implications.

A mix of high population and rising consumption means that humanity is currently outstripping the biological capacity of the Earth by 25% a year. By 2050, when global population is projected at 9.2 billion - 2.5 billion rise - humans will be using the biocapacity of two earths.

The report suggests compulsory limits on births may become unavoidable in as more pressure is put on world resources.

Prof Guillemaud says: "No one is in favour of governments dictating family size but we need to act quickly to prevent it. Worldwide, those who continue to place obstacles in the way of women who want to control their fertility will have only themselves to blame, as more and more regimes bring in coercive measures.

"Despite the catastrophic current increase of an extra 1.5 million humans per week, there is still a slim chance that such measures can be avoided."