A trans woman in Houston, Texas, has been arrested after using a female toilet in a library.

Tyjanae Moore was arrested by police last Wednesday for “knowingly entering a restroom of the opposite sex” but trans groups say her arrest was unlawful.

Ms Moore said she told police she was in the process of transitioning.

She pleaded guilty to using an opposite gender restroom and was given credit for the two nights she spent in jail.

Speaking to Fox News, Ms Moore said: “I felt so belittled going to a jail over something so simple and stupid.

“When I came out, the female [officer] told me I wasn’t supposed to be and I asked if there was any particular reason why not. She said I’m a transgendered female and I was really shocked that they even stopped me for this.”

Trans groups say her arrest was unlawful because a city ordinance passed by Houston this year allows trans people to use the toilets which correspond to their new sex.

The ordinance says: “It shall be unlawful for any person to knowingly and intentionally enter any public restroom designated for the exclusive use of the sex opposite to such person’s sex without the permission of the owner, tenant, manager, lessee or other person in charge of the premises, in a manner calculated to cause a disturbance.

Cristan Williams, executive director of the Transgender Foundation of America, which is based in Houston, said: “The arrest should have never happened.

“The City of Houston has given this victim explicit permission to use a restroom consistent with their gender.

“This means that the library patron was acting in a manner consistent with both state and local law. Since she broke no law, this is a case of unlawful arrest and imprisonment.”