Britain is preparing to rip up centuries-old rules by introducing passports which do not contain details of the holder’s sex.

The move, following pressure from the Lib Dems, is designed to spare transgender people and those who have both male and female sexual organs from having to tick “male” or “female” on their travel papers.

Currently, everybody must identify themselves as a man or woman, even when they are undergoing a sex-change operation or if they are considered “intersex”.

But with the Lib Dems promising to be “fierce champions of equality”, the Home Office has begun a consultation on changing the rules.

To satisfy international laws, the passport would still list a category titled “sex”, but would then contain a simple “X” for everybody.

Supporters say it will solve the problem of embarrassing situations at border controls, where people whose sex appears to differ from that in their passport are grilled for long periods by guards.

But some Home Office officials are concerned the change could make life harder for the already stretched UK Border Agency by giving them one fewer piece of information to work from.

The Home Office said: “We are exploring with international partners and relevant stakeholders the security implications of gender not being displayed in the passport.”

Home Office Minister Lynne Featherstone is under pressure to act from her fellow Lib Dem MPs.

One backbench MP, Julian Huppert, said: “There does not seem to be a need for identity documents of any kind to have gender information. It is not a very good biometric; it is roughly a 50:50 split. Military ID, such as the MOD90, which obviously can have quite a high security clearance, contains no gender information. That might be what we should look at.”

Mrs Featherstone - who has just announced plans for gay weddings - has made a string of promises committing the Government to do more for transgender people.

She said: “The UK Government is totally committed to creating a society that is fair for everyone.

“We are committed to tackling prejudice and discrimination against transgender people at home and around the world. We need concerted government action to tear down barriers and help to build a fairer society for transgender people.”

And she said in a speech on Saturday: “While on my travels as a champion for women’s rights, I am and will be a champion for gay rights too. Britain must not get complacent. We are a world leader for gay rights, but there is still more that we must do.”

Under existing rules, a “transgender” person undergoing a sex-swap is free to change their identity to a new sex, once the procedure is complete and a gender recognition certificate has been issued.

While undergoing a sex change, a person can also nominate their intended new sex, and place that on their passport. They must produce a certificate from a doctor saying that is the gender under which they live their daily lives.

But people who are classed as intersex - a condition which people carry from birth, where they have male and female reproductive organs - are forced to make a choice.

Home Office officials say the review is wide-ranging and they are considering “all the gender options”.

The law in Britain could be changed in a matter of days. Passports come under the royal prerogative, so only a simple ministerial order would be required.

An Identity and Passport Service spokesman said: “IPS is considering the gender options available to customers in the British passport.

“This is at the early discussion stage and no decisions have been taken. Any changes to the UK passport would need to satisfy our rigorous security requirements.” - Daily Mail