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."
Archbishop of Canterbury Rowan Williams, spiritual leader of the world's 77 million Anglicans, said 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.
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.
In The Times, columnist Bronwen Maddox said the verdict was "something of a fudge ... designed to give a nod to British reproof but also to appease the street."
Britain's response - applying diplomatic pressure while extolling ties with Sudan and affirming respect for Islam - had produced mixed results, British commentators concluded.
In an editorial, The Daily Telegraph said Miliband "has tiptoed around the case, avoiding a threat to cut aid and asserting that respect for Islam runs deep in Britain. Given that much of the government's financial support goes to the wretched refugees in Darfur and neighboring Chad, Mr. Miliband's caution is understandable."
Now, however, the newspaper said, Britain should recall its ambassador in Khartoum and impose sanctions on the Sudanese regime.