KHARTOUM — Thousands of Sudanese, many armed with clubs and knives, rallied yesterday in a central square and demanded the execution of a British teacher convicted of insulting Islam for allowing her students to name a teddy bear “Muhammad.”

In response to the demonstration, teacher Gillian Gibbons was moved from the women’s prison near Khartoum to a secret location for her safety, her lawyer said.

The protesters streamed out of mosques after Friday sermons, as pickup trucks with loudspeakers blared messages against Ms. Gibbons, who was sentenced Thursday to 15 days in prison and deportation. She avoided the more serious punishment of 40 lashes.

They massed in central Martyrs Square outside the presidential palace, where hundreds of riot police were deployed. They did not try to stop the rally, which lasted about an hour.

“Shame, shame on the U.K.,” protesters chanted.

They called for Ms. Gibbons’ execution, saying, “No tolerance: Execution,” and “Kill her, kill her by firing squad.”

Ms. Gibbons’ chief lawyer, Kamal al-Gizouli, said she was moved from the prison for her safety for the final nine days of her sentence.

“They moved this lady from the prison department to put her in other hands and in other places to cover her and wait until she completes her imprisonment period,” he said, adding that she was in good health.

“They want, by hook or by crook, to complete these nine days without any difficulties, which would have an impact on their foreign relationship,” he said.

Several hundred protesters, not openly carrying weapons, marched from the square to Unity High School, about a mile away, where Ms. Gibbons worked. They chanted slogans outside the school, which is closed and under heavy security, then headed toward the nearby British Embassy. They were stopped by security forces two blocks away from the embassy.

The protest arose despite vows by Sudanese security officials the day before, during Ms. Gibbons’ trial, that threatened demonstrations after Friday prayers would not take place. Some of the protesters carried green banners with the name of the Society for Support of the Prophet Muhammad, a previously unknown group.

Many protesters carried clubs, knives, and axes — but not automatic weapons, which some have brandished at past government-condoned demonstrations. That suggested yesterday’s rally was not organized by the government.

A Muslim cleric at Khartoum’s main Martyrs Mosque denounced Ms. Gibbons during one sermon, saying she intentionally insulted Islam. He did not call for protests, however.

“Imprisoning this lady does not satisfy the thirst of Muslims in Sudan. But we welcome imprisonment and expulsion,” the cleric, Abdul-Jalil Nazeer al-Karouri, a well-known hard-liner, told worshippers.

“This an arrogant woman who came to our country, cashing her salary in dollars, teaching our children hatred of our Prophet Muhammad,” he said.

Britain, meanwhile, pursued diplomatic moves to free Ms. Gibbons. Prime Minister Brown spoke with a member of her family to convey his regret, his spokeswoman said.

“He set out his concern and the fact that we were doing all we could to secure her release,” spokeswoman Emily Hands told reporters.

Most Britons expressed shock at the verdict by a court in Khartoum, alongside hope it would not raise tensions between Muslims and non-Muslims in Britain.

“One of the good things is the U.K. Muslims who’ve condemned the charge as completely out of proportion,” , a student in London, Paul Wishart, 37, said.

“In the past, people have been a bit upset when different atrocities have happened and there hasn’t been much voice in the U.K. Islamic population, whereas with this, they’ve quickly condemned it.”

A secretary-general of the Muslim Council of Britain, Muhammad Abdul Bari, accused the Sudanese authorities of “gross overreaction.”

“This case should have required only simple common sense to resolve. It is unfortunate that the Sudanese authorities were found wanting in this most basic of qualities,” he said.

The Muslim Public Affairs Committee, a political advocacy group, said the prosecution was “abominable and defies common sense.”

The Federation of Student Islamic Societies, which represents 90,000 Muslim students in Britain and Ireland, called on Sudan’s government to free Ms. Gibbons, saying she had not meant to cause offense.

“We are deeply concerned that the verdict to jail a schoolteacher due to what’s likely to be an innocent mistake is gravely disproportionate,” the group’s president, Ali Alhadithi, said.

The Ramadhan Foundation, a Muslim youth organization, said President al-Bashir of Sudan should pardon the teacher.

“The Ramadhan Foundation is disappointed and horrified by the conviction of Gillian Gibbons in Sudan,” spokesman Mohammed Shafiq said.

Archbishop of Canterbury Rowan Williams, spiritual leader of the world’s 77 million Anglicans, said Ms. Gibbons’ prosecution and conviction was “an absurdly disproportionate response to what is at worst a cultural faux pas.”

Foreign Secretary David Miliband summoned the Sudanese ambassador late Thursday to express Britain’s disappointment with the verdict. The Foreign Office said Britain would continue diplomatic efforts to achieve “a swift resolution” to the crisis.

Ms. Gibbons was arrested Sunday after another staff member at the school complained that she had allowed her 7-year-old students to name a teddy bear Muhammad. Giving the name of the Muslim prophet to an animal or a toy could be considered insulting.

The case put Sudan’s government in an embarrassing position — facing the anger of Britain on one side and potential trouble from powerful Islamic hard-liners on the other. Many saw the 15-day sentence as an attempt to appease both sides.