Couples who have more than two children are putting an 'irresponsible' burden on the environment, a former Government's green adviser warned.
Jonathon Porritt called on ministers to take action to reduce population growth in Britain, and criticised fellow green campaigners for ducking the 'controversial' issue.
Mr Porritt, who was chairman of the Sustainable Development Commission, which advises the Government on green matters, said the SDC was due to publish a report on the subject. It is thought he wants the Government to divert money away from curing illnesses so it can fight global warming by funding family-planning services, including abortion and contraception.
Mr Porritt, himself a father of two, said: 'I am unapologetic about asking people to connect up their own responsibility for their total environmental footprint and how they decide to procreate and how many children they think are appropriate. 'I think we will work our way towards a position that says having more than two children is irresponsible. Ã¢Â€Â˜It is the ghost at the table. We have all these big issues that everybody is looking at and then you don't really hear anyone say the P-word [population].
'My mission with the Friends of the Earths and the Greenpeaces of this world is to say, 'You are betraying the interests of your members by refusing to address population issues and you are doing it for the wrong reasons because you think it is too controversial'.' He added: 'We still have one of the highest rates of teenage pregnancies in Europe and we still have relatively high rates of pregnancies going to birth, often among women who are not convinced they wish to become mothers.'
Britain's population of 61 million is forecast to exceed 70 million by 2028. The birth rate is now at its highest for almost 30 years, largely because of high immigrant birth rates, and because of our high teenage pregnancy rates.
But Mr Porritt's views caused outrage among anti-abortion campaigners.
A spokesman for the Pro-life Alliance said: 'The unpleasant aspect of this is the idea that how many children you have should be down to the state. 'Wherever we have seen such policies being imposed, such as in China, we have seen a preference for male children and a rise in infanticide.'
Campaigners say each baby born in Britain will, during his lifetime, burn the amount of carbon equivalent to the size of Trafalgar Square.
The row came as the Roman Catholic Church, which views contraception as 'intrinsically evil', compared environmentalism to Marxism. A booklet by the London-based Catholic Truth Society, a charity under the patronage of Peter Smith, the Archbishop of Cardiff, said environmental lobby tended to exaggerate the threat to vindicate its calls for radical Government measures. The book, Global Warming: How Should We Respond?, says: 'Just as Marxism advocated communism as the only solution to the world's ills, so Greens warn us of major catastrophe if we do not adopt their calls for radical change.' It says the ideology of the Green movement runs counter to Christian beliefs, because it sees Ã¢Â€Â˜mankind as just one species among many'. The book says that population programmes targeting the 'supposedly feckless breeding' of the poor, especially in developing countries, were the result of racist and unfounded prejudices.
'Environmental campaigns which demand that the natural world should be treated with greater respect imply that this is the only issue that matters, ignoring the plight of humanity or any spiritual values,' it said.