Political parties will be forced to declare how many women, ethnic minority and disabled applicants they reject as candidates in an attempt to change Parliament's image as a club of middle class, middle-aged men.
An inquiry chaired by the Commons Speaker, John Bercow, called yesterday for much greater efforts by the parties to ensure that the House of Commons is "fit for the 21st century".
In future, parties will publish online every six months details of the candidates they are selecting for the next general election. An amendment to the Equality Bill, now going through Parliament, will ensure there is "public accountability" to the secretive process of candidate selection.
The all-party Speaker's Conference said parties were the "gatekeepers" to the Commons and had to be the agents of change but that their record on promoting diversity was "uneven".
Its inquiry found that while more women and black and Asian people were trying to become candidates, "the fact remains that at present the House of Commons continues to be largely white, male, middle-aged and middle class."
It added: "People from under-represented groups who are putting themselves forward for selection are still proportionately less likely to be selected, or to be selected for a seat the party thinks it can win, than their counterparts."
The inquiry found that parties only monitored their progress internally, so there was no public accountability. It said: "Unless the performance of different parties can be compared with each other (and with the performance of parties throughout the world) there is likely to be insufficient pressure for the political parties to pursue the cultural change which is needed from them before we can have a House of Commons fit for the 21st century."
Although all parties are committed to boosting the number of women, black and Asian and disabled MPs, the Speaker's Conference found there was little information in the public domain about the people seeking nomination who fail to become candidates. "To monitor progress properly requires data from all stages of the selection process, from the initial call for applicants to the final outcome. Otherwise we will only ever know about the individuals who are successful," said its report.
The conference was told that fewer disabled and openly gay people were putting themselves forward as candidates than women, black and Asian and disabled people. It is also looking into representation of the lesbian, gay, bisexual and transsexual community.
Scope, the disability charity, backed the conference's proposal but said more needed to be done to remove the obstacles to disabled people entering Parliament. Abigail Lock, its head of advocacy and campaigns, said: "This is an encouraging development to help increase Parliament's diversity. However, whilst monitoring the number of unsuccessful parliamentary candidates will be helpful, this needs to be accompanied by firm action to tackle the range of barriers that effectively lock people from minority groups out of the selection process.
"Disabled people in particular are shockingly under-represented in British public life. One of the biggest barriers they face is a lack of financial support to help meet the extra costs associated with their impairment, such as sign language interpreters."