Nicolas Sarkozy's centre-right party has put forward legislation that would see women make up half the figures in France's leading boardrooms by 2015, under a bold plan to impose gender equality on the male-dominated business world.

In a bill submitted to the French parliament this week, all companies listed on the Paris stock exchange would have to ensure female employees made up 50% of their board members by 2015. If passed, a gradual implementation of the law would see businesses obliged to have women in 20% of board seats within 18 months, and 40% within four years.

Jean-François Copé, president of the majority UMP party, said it could give a "much-needed electro-shock" to the French corporate world, long considered a bastion reserved for the male elite in which only 10.5% of board members in CAC 40 (French stock market index) companies are female.

Referring to France's move in 2000 to encourage gender equality in politics, he said: "We must do to companies what we did in the public domain a few years ago and impose parity."

The proposals, which would also apply to state-owned companies and non-listed firms with supervisory boards, will be debated next month and would need the approval of both houses of parliament to become law.

Despite the historically entrenched opposition of business chiefs to quotas, advocates say the bill is the result of a sea change in public attitudes towards gender equality. Over the past year a series of French figures not known for their feminist stance have spoken out in favour of quotas.

Daniel Lebègue, president of the conservative French Institute of directors (IFA), said his organisation had reluctantly decided they were the only way of encouraging progress. Nadine Morano, the secretary of state for the family, has said quotas are a "necessary evil", while the president of Areva, Anne Lauvergeon, recently admitted she had changed her mind about a strategy she nonetheless acknowledged as "humiliating".

Véronique Préaux-Cobti, a leading businesswoman, said the discussions were a sign that times had changed.

"In 2002, a huge majority would have been against," she told Le Figaro earlier this year. "Now, after years of good will with no change, there is a real realisation that things are not going to change on their own."

Cope and the bill's other author, the UMP's Marie-Jo Zimmermann, are determined to capitalise on the change in public opinion to drive through the reforms. Inspired by the example set in Norway, where enforced quotas have led to 40% of director posts being occupied by women, they say they are willing to take on the "reserves" of several government ministers.

Their boss, President Sarkozy, was congratulated in 2007 for appointing seven women to his 15-member cabinet. However three of those, including former Justice Minister Rachida Dati, have since been replaced, giving rise to one news weekly wondering if he was starting to show his true "macho" colours.

France's failure to impose parity on its politicians, despite a constitution change in 2000 which had the aim of giving women a larger presence in the French parliament, is one of the reasons many people remain sceptical about this week's proposals. At the last election, only 18% of MPs in the lower house were women.

Françoise de Panafieu, one of those MPs, hit out today at her own party for setting out quotas for the business world when it had failed to put its own house in order. "I prefer people setting an example to those giving lessons," she told L'Express magazine, claiming that Sarkozy's party had had to pay €5m (£4.5m) in fines after the 2007 elections for failing to impose parity.

The Norway way

Norway was the pioneer in introducing legislation to boost the number of women on company boards, in 2003. The change in the law affected nearly 500 public companies, including 175 firms listed on the Oslo stock exchange. Ministers stipulated that businesses should increase the number of women on their boards to 40% or face the threat of closure.

It unleashed an uproar in the Norwegian business community, with many protesting it was ridiculous to shut down a company because it lacked a woman on the board. Others argued that the law infringed the rights of shareholders to decide who they want as directors. But the threat worked and company owners duly complied. Norway now has the highest proportion of women on boards anywhere in the world with 44.2% – up from 6% in 2001. By comparison, in the UK, 12% of FTSE 100 directors are female and one in four boards are exclusively male. Sweden and Finland boast more women at leading companies at 22% and 17% respectively.

The proportion of female directors among US Fortune 500 firms is 15.2%.