A new buy-in-bulk deal to provide cheaper contraception for developing countries is set to be finalised by a coalition of governments and private donors headed by Bill Clinton and a leading drug company, potentially helping up to 27 million women.

The former US president, announcing the project at the United Nations, said the contract would bring down the costs of 'Jadelle', a reversible progestogen implant inserted into the arm which can provide contraception for five years.

It will be distributed to women in 42 countries including Bangladesh, Kenya and Senegal with the hope that families without access to other forms of contraception can gain more control over their family planning. Strategists hope this will cut the number of maternal deaths in childbirth and large families suffering from child starvation. "This would actually save about 280,000 children's lives. They might be born a year or so late. They may be born in greater spacing but they will live and be healthy," Mr Clinton said.

The United Kingdom and Norway are among countries paying into the deal and his Clinton Global Initiative (CGI) was attracting support from donors at a high-end fund-raiser in New York last week.

Mr Clinton told The Independent on Sunday: "Smart billionaires are very worried about growing inequality in the world. You get them together and prove that it makes good sense that everybody wins. Bill Gates is giving his money away. He is a very smart man and he knows that it is a severe constraint on the future growth of the world if there is too much income inequality if life chances are not fairly distributed." He added: "Let me tell you why this is a watershed moment. The difference today from what we have done in the past is a that we have a whole coalition of donors and counties working together to pull their resources."

A spokeswoman for the German manufacturers of the implant, Bayer Health Care, said: "The current price of the contraception implant Jadelle will be cut from $18 (£11) to $9."