A Government environment adviser has said that couples who have more than two children create an unbearable burden on the environment.
Jonathon Porritt, who chairs the Government's Sustainable Development Commission, said that curbing population growth through contraception and abortion is key to combating climate change.
Mr Porritt, who has two children, argues the government must promote more effective family planning.
"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," he said.
"I think we will work our way towards a position that says that having more than two children is irresponsible. It is the ghost at the table."
Britain's current population of 61 million people is expected to exceed 70 million by 2028, while the world's current population of 6.7 billion people is expected to rise to 9.2 billion by 2050, according to The Sunday Times.
A report by the commission, due to be published next month, will say that governments must reduce population growth through better family planning.