Legislators in Arizona want to ban transgender people from using public toilets, showers and dressing rooms not associated with their birth gender, in the latest tussle over equal rights in the US state.

The proposal comes less than a month after the Phoenix passed a human rights bill prohibiting gender identity discrimination in public accommodations.

Arizona's Republican representative, John Kavanagh, has been campaigning to make it a criminal offence for a transgender person to use a public facility associated with a gender other than what is recorded on his or her birth certificate.

Gender equality advocates and transgender groups say if the proposed law is passed it would be the toughest of its kind in the country.