The Government is facing a call from MPs to legislate to ensure at least 45 per cent of parliamentary candidates fielded by political parties are women.
The Commons Women and Equalities Committee said the lack of women MPs relative to the numbers of men represented a “serious democratic deficit”.
It called on ministers to set a target for 45 per cent of all representatives in Parliament and in local government to be women by 2030.
It said the goal should be backed by legislation setting a statutory minimum proportion of female parliamentary candidates in general elections for each political party, with fines or other sanctions for those that failed to comply.
“While the goal is equality, we recognise the difficulty inherent in setting this statutory minimum at 50 per cent; such a precise target would be difficult to meet while also ensuring that men did not become under-represented.
“A minimum of 45 per cent would therefore be acceptable,” it said.
It urged the Government to bring forward legislation in the current parliament so that the new requirements could be brought into force if the proportion of women MPs does not increase significantly at the next general election in 2020.
Currently, the committee said, just 30 per cent of MPs are women with the UK ranking 48th globally for female representation in the lower or single legislative chamber, having fallen back from 25th place in 1999.
While all the main party leaders had made commitments to increase their tally of women MPs, the committee said it had seen little evidence of any “robust work” within parties to assess their likely effectiveness or setting out detailed road maps for implementing them.
It said ministers should now invoke statutory powers contained in the Equality Act 2010 requiring parties to publish their candidate diversity data for general elections while providing the Electoral Commission with new powers to collect and host the information.
“Women make up more than half the population of the United Kingdom and, at a time when more women are in work than ever before, there is no good reason why women should not make up half of the House of Commons,” it said.
“If the Commons is serious about being truly representative of the people that it seeks to represent, it must rise to the challenge of being a world leader on women’s parliamentary representation.”
In other recommendations, the committee called for the provisions of the Sex Discrimination (Election Candidates) Act 2002 to be extended so the parties can continue to operate all-women shortlists after 2030 - as well as extending them to cover elected mayors and police and crime commissioners.
The committee chairwoman, Conservative former culture secretary Maria Miller, said: “In their evidence to our inquiry, the leaders of political parties agreed that the Commons would benefit from gender equality, and a range of initiatives is in place to improve the situation.
“But we saw little to justify their confidence that these will be sufficient.
“We need concrete action plans. We need party leadership to provide clear and strong direction in working with local parties to deliver more women candidates. We need to see more women candidates in winnable seats.
“Above all, parties need to be transparent and accountable in their progress - or the lack of it.”