BANGKOK (REUTERS) - Women lawyers in Thailand are petitioning to change a dress code that bars them from wearing trousers in court, saying the regulations are sexist and discriminatory.

The Human Rights Lawyers Association said it would ask the Lawyers Council of Thailand to revise a decades-old requirement that female lawyers wear "international and polite attire", including a skirt and shoes with a closed back.

"Women should have the freedom to dress and not be restricted to wearing only skirts," said Ms Koreeyor Manuchae, a lawyer representing the association who has twice been reprimanded for wearing trousers in court.

"We shouldn't feel that wearing trousers is bad and is a crime. As a Muslim woman, if I wear a skirt it must be as long as my heels, and wearing such a long dress isn't convenient."

The Lawyers Council of Thailand was not immediately available for comment.

A code of ethics handbook for new lawyers includes photos of women wearing black skirts to below the knees and court shoes.

Lawyers who break the rules can face a range of penalties, from a reprimand to having their licence revoked.

While such a regulation exists for female lawyers, government officials and public prosecutors are allowed to wear trousers as part of their uniform.

Ms Kunanya Songsamuth, a human rights lawyer who signed the petition, said she wears skirts to attend court even though she never wears one in her daily life.

"I don't have the courage to wear trousers because I've never seen any lawyer do that. (Wearing a skirt) makes me lack confidence," she said. "When I'm done with court, I always bring a pair of trousers to change."