Police fired teargas and beat supporters of a Sudanese woman facing 40 lashes for wearing trousers in public shortly before her trial was adjourned this morning.

Police in Khartoum moved in swiftly and dispersed about 50 protesters, mostly women, who were supporting Lubna Hussein, a former UN worker charged with indecent dressing in violation of the country's Islamic laws.

Some of the women demonstrators wore trousers in solidarity with Hussein. We are here to protest against this law that oppresses women and debases them, said Amal Habani, a female columnist for the daily newspaper Ajraa al-Hurria (Bells of Freedom).

Hussein's trial was later adjourned until September by a judge to seek clarification from Sudan's foreign ministry over her status.

Hussein, who wore the same trousers to court as on the day of her arrest, said she was resigning from her job to have the chance to prove her innocence.

At the time of her arrest, Hussein was working for the media department of the UN mission in Sudan, which gives her immunity from prosecution. She submitted her resignation after her trial began last week because she wanted to go on trial to challenge the dress code law. A defence lawyer, Jalal al-Sayed, said the judge wanted to know whether Hussein still had immunity because her employers were still to accept her resignation.

The trial is seen as a test case of Sudan's harsh indecency laws.

The Sudanese woman journalist on trial for wearing trousers in public said she was prevented from leaving the country Tuesday for a trip to Lebanon, where she was to take part in a televised talk-show about women's issues.

Lubna Hussein could receive 40 lashes if found guilty of violating Sudan's indecency law which follows a strict interpretation of Islam.

Hussein, who has been released on bail during the hearings, has sought to draw international attention to her case and battle the law she described as un-Islamic and oppressive to women. Her trial resumes in September.

She was stopped at Khartoum airport. She was told that she was barred from traveling and was shown a ban signed by the public order police, which has raised the charges against her.

Travel bans are usually issued in major criminal cases when there is a risk of a defendant fleeing the country.

It seems that wearing trousers is now a serious crime in Sudan, Hussein said later.

A Sudanese woman has said that she would continue her campaign of defiance after being convicted by a court of indecency for wearing trousers in public.

Lubna Hussein said she would refuse to pay the 500 Sudanese pound (£127) fine imposed on her by a judge who ruled that she should not face a punishment of 40 lashes.

Hussein was among 13 women arrested in July during a raid at a party by the police in Khartoum. Ten of the women were fined and flogged two days later. But Hussein and two others decided to go to trial.

I will not pay a penny, said Hussein, who stated last week that she would rather go to jail than pay any fine. I won't pay, as a matter of principle. I would spend a month in jail. It is a chance to explore the conditions of jail.

Amnesty International has called on the Sudanese government to withdraw the charges against Hussein and repeal the indecency law, which it said justifies abhorrent penalties.

The case is being seen as a test of Sudan's Islamic decency regulations, which many female activists claim are too vague and give undue latitude to individual police officers to determine what is acceptable clothing.

Lubna has given us a chance. She is very brave. Thousands of girls have been beaten since the 1990s, but Lubna is the first one not to keep silent, one protester, Sawsan Hassan el-Showaya, told Reuters.

About 150 protesters – most of them women, including some in trousers – had gathered on a traffic island to wave banners outside the court, hemmed in by security guards and riot police. The women were later confronted by dozens of men in traditional Islamic dress who shouted religious slogans and denounced Hussein and her supporters, describing them as prostitutes and demanding harsh punishment for Hussein.

Hussein's lawyer, Nabil Adib Abdullah, has said the law on indecent dress is so wide that it contravenes a person's right to a fair trial. Hussein challenged the charges, arguing that her clothes were respectable, so she did not break the law.

A Sudanese woman who was imprisoned for wearing trousers deemed indecent has been released after the country's journalist union paid a $200 fine on her behalf.

Lubna Ahmed al-Hussein, who had been found guilty of flouting the country's decency laws, said after being released that the fine had been paid without her permission.

I am not happy. I told all my friends and family not to pay the fine, she said.

A Khartoum court on Monday ordered al-Hussein to pay a fine or face a month in jail, but she was spared a possible penalty of 40 lashes. Al-Hussein refused to pay, preferring to go to jail as a means of challenging Sudan's public order act.

A Sudanese woman who was punished for breaching decency laws by wearing trousers has defied a travel ban by coming to France to publicise her new book.

Lubna Hussein was arrested in July and convicted of indecency charges in a case that made headlines worldwide. She was ordered to pay a fine or face a month in jail, but was spared an initial penalty of 40 whip lashes.

I was banned from leaving Sudan by air, by land or by sea and I succeeded in getting out ... so I am sure this book will surface in Sudan, she told Reuters in an interview.

Her book, Forty lashes for a pair of trousers, has come out in French and will be translated into English, Arabic, Swahili and other languages.

It details Hussein's arrest in July with 12 other women for wearing indecent clothing, a pair of green slacks. No one has been able to find a text in the Koran which justifies flogging a woman for the way she is dressed, said Hussein.

Silva Kashif, 16, was lashed 50 times after receiving the sentence from a Sudanese judge, who ruled her knee-length skirt to be indecent.

The teenager was arrested while walking to the market in Khartoum. The police officer took her immediately before a Sharia court, and whipped by another police officer after being ordered by the judge to do so.

The girl's mother, Jenty Doro, told Reuters: She is just a young girl but the policeman pulled her along in the market like she was a criminal. It was wrong. I only heard about it after she was lashed. Later we all sat and cried ... People have different religions and that should be taken into account.

Because the family is Christian and the girl is a minor, they are planning on filing a lawsuit.

The family's lawyer Azhari al-Haj said: She was wearing a normal skirt and blouse, worn by thousands of girls. They didn't contact a guardian and punished her on the spot.