The third sex has received official recognition in Australia as travellers from Down Under can now select from three gender options on their passports -- male, female and 'x'.
The new category is only for use by intersex people -- who are not biologically entirely male or female, Daily Mail reported.
Transgender passport-holders -- who have changed gender but not had surgery -- will be free to choose either male or female, but will not be allowed to select 'x'.
Earlier, travellers were not able to change sex on their passport unless they had had surgery. This is still the case in many countries, although any nation under the International Civil Aviation Organisation's authority may introduce category 'x'.
Australian senator Louise Pratt, whose partner was born female and now lives as a man, said: "It's a really important recognition of people's human rights that if they choose to have their sex as "indeterminate", they can."
Australia's foreign minister Kevin Rudd said: "This amendment makes life easier and significantly reduces the administrative burden for sex and gender diverse people who want a passport that reflects their gender and physical appearance."
Peter Hyndal, who negotiated with the Australian government on the reforms on behalf of human rights advocacy group A Gender Agenda, said the new guidelines were in line with more flexible approaches to gender in US and British passports.