Gay and unmarried MPs are to be given free train and plane tickets for partners in a shake-up of House of Commons equal-opportunity rules ordered by the Speaker.

Travel warrants, which entitle the spouses of MPs to free first-class travel to and from London and their constituencies, are to be extended to the partners of unmarried MPs.

The move follows protests from MPs who are not married that they are having to pay travel expenses when partners visit London. Michael Martin, the Speaker, has asked his advisory panel of MPs to come up with a solution that will stop the discrimination.

Stephen Byers and Alan Milburn are among MPs in long-term relationships who have not married. Gay MPs, including Chris Bryant, Labour MP for Rhondda, are also denied the travel perks.

Gay-rights campaigners welcomed the review yesterday. "I think it's part of coming into the 21st century. To deny travel warrants to same-sex partners is ridiculous," said Angela Mason, executive director of Stonewall.

A spokesman for Mr Martin said he acknowledged the ban was outdated and in need of reform. "He's committed to modernising this system," he said. "The question we are looking at is how we do it as it's quite complex."

The Speaker's advisory panel, chaired by Anne Campbell, Labour MP for Cambridge, is examining how to revise the system. One issue being looked at is allowing MPs to nominate the name of one person who will be entitled to a "spouse's warrant" – regardless of marital status.

The review is complicated because of the implications it could have for tax and for civil servants who will also want a review of benefits.