Thousands of Sudanese, many armed with clubs and knives, rallied Friday 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."
The protesters streamed out of mosques after Friday sermons, as pickup trucks with loudspeakers blared messages against Gillian Gibbons, the teacher 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, although they did not try to stop the rally.
"Shame, shame on the U.K.," protesters chanted.
They called for Gibbons' execution, saying, "No tolerance: Execution," and "Kill her, kill her by firing squad."
The women's prison where Gibbons is being held is far from the site. Unity High School, which is closer by in central Khartoum, is under heavy security protection.
The protest arose despite vows by Sudanese security officials the day before, during 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 Friday's rally was not organized by the government.
A Muslim cleric at Khartoum's main Martyrs Mosque denounced 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 Gibbons. Prime Minister Gordon 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," said Paul Wishart, 37, a student in London.
"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."
Muhammad Abdul Bari, secretary-general of the Muslim Council of Britain, 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."