Lawmakers in Arizona are weighing a law requiring transgender people to use public toilets of the gender listed on their birth certificate.

Transgender protesters forced a halt to debate on the bill on Wednesday.

Last month, the state approved a human rights measure banning gender identity discrimination at public facilities.

In recent weeks, two other states passed laws ensuring equal access to gender-segregated facilities for transgender students.

The bill in Arizona's Republican-dominated legislature would make it a misdemeanour offence to use a public toilet, bathroom, shower, bath, dressing room or changing room associated with a gender other than what is on one's birth certificate.

'Making everyone uncomfortable'

Penalties could include six months in prison.

This law simply restores the law of society: men are men and women are women John Kavanagh, Sponsor of the bill

"If you look like a man and you live your life like a man, you should be able to use a man's bathroom," said Dru Levasseur, a transgender rights lawyer for the advocacy group Lambda Legal.

But John Kavanagh, the Republican lawmaker who sponsored the bill, said he feared criminals might take advantage of the situation and expose themselves to children of the opposite gender.

"This law simply restores the law of society: men are men and women are women," Mr Kavanagh said, according to the Associated Press.

"For a handful of people to make everyone else uncomfortable just makes no sense."

But, Mr Kavanagh added, police would be allowed to use their discretion over whether to press charges if women used the men's room to avoid a long queue.

On Wednesday, Mr Kavanagh agreed to postpone a vote on the bill at the start of a hearing filled with dozens of transgender activists.

The bill's opponents say it would force transgender people to reveal themselves and risk harassment,

"Most transgender people try to slip through public places without being noticed,'' activist Erica Keppler said.

"This will turn us into criminals."

And advocates say transgender people can find it difficult to change gender on their birth certificates because many states require proof of gender treatment surgery.

Meanwhile, other states such as Idaho and Ohio do not allow such changes at all, the American Civil Liberties Union said.

It is already illegal to discriminate against transgender people in 16 US states, although the extent of protections can vary, the group added.

In an ongoing case, a Colorado family has filed a complaint against the state after their six-year-old, who was born a boy, was banned from using the girl's bathroom at her primary school.