KHARTOUM, Sudan (CNN) -- Hundreds of protesters brandishing swords and sticks gathered outside Khartoum's presidential palace Friday to vent their anger against a British teacher jailed for allowing children to name a teddy bear "Mohammed."
An undated amateur photo of Gillian Gibbons, who has been found guilty of insulting religion.
About 600 Islamic demonstrators piled out of mosques, chanting: "By soul, by blood, I will fight for the Prophet Mohammed." Some of the protesters demanded the teacher's execution, according to The Associated Press.
The agency reports that some chanted: "No tolerance: Execution," and "Kill her, kill her by firing squad."
The decision by a Sudanese court to jail Gillian Gibbons late Thursday was widely criticized outside Sudan as too harsh, with British Foreign Secretary David Miliband saying he was "extremely disappointed" the charges were not dismissed.
Abdul-Jalil Nazeer al-Karouri, a prominent cleric and hardliner, told worshippers Friday at the Martyrs Mosque: "Imprisoning this lady does not satisfy the thirst of Muslims in Sudan. But we welcome imprisonment and expulsion," according to AP. But he did not urge worshippers to protest.
In leaflets distributed earlier this week by Muslim groups and seen by CNN, the protesters promised a "popular release of anger" at demonstrations called for Friday.
The leaflets condemned Gibbons as an "infidel" and accused her of "the pollution of children's mentality" by her actions.
The teacher was convicted of insulting religion but cleared of two other charges of inciting hatred and showing contempt for religious beliefs, Ali Ajeb, her lawyer said. Watch latest developments in the case 
Ajeb said they were planning to appeal the sentence, which runs from the date she was first detained, November 25.
Gibbons, 54, is being held in a woman's prison in the Omdurman district of Khartoum and she will be deported at the end of her prison term, British consular officials in the city told CNN.
Embassy staff said they were giving the teacher, from the northern English city of Liverpool, full consular assistance. 
Watch a report on reactions to the verdict »
Omer Mohammed Ahmed Siddig, the Sudanese ambassador to Britain, was summoned for a second time to meet with the British foreign secretary late Thursday after the court's ruling.
Miliband also spoke to the Sudanese acting foreign minister for 15 minutes on the telephone during the meeting, the British Foreign Office said.
"Our priority now is to ensure Ms. Gibbons' welfare and we will continue to provide consular assistance to her," Miliband said in a statement.
The Foreign Office said there would be further talks with the Sudanese government Friday.
Gibbons was arrested Sunday after she asked her class of seven-year-olds in Khartoum to name the toy as part of a school project, the Foreign Office said.
She had faced charges under Article 125 of Sudan's constitution, the law relating to insulting religion and inciting hatred.
She could have faced a sentence of 40 lashes, a fine or jail term of up to a year, according to the Foreign Office, which expressed Britain's dissatisfaction with the verdict.
British newspapers condemned Gibbons' conviction, with The Daily Telegraph calling for the recall of the British ambassador from Khartoum and sanctions against the heads of the Sudanese government.
In an editorial the tabloid newspaper, The Sun, said Gibbons' jailing was a "grotesque insult to Islam" and called Gibbons "an innocent abroad."
Four vans filled with riot police were stationed outside the courthouse at Thursday's hearing, but there were no signs of street disturbances or protests.
Staff from Gibbons' school, including Robert Boulos, the head of Unity High School, were present.
Boulos said he was "horrified" when he found out it was a member of his own staff who complained, not a parent as originally thought.
Defense counsel later confirmed that the complaint came from Sarah Khawad, a secretary at the school.
Gibbons has been working at the school -- popular with wealthy Sudanese and expatriates -- since August, after leaving her position as deputy head teacher at a primary school in Liverpool this summer, Boulos said.
He said Gibbons asked the children to pick their favorite name for the new class mascot, which she was using to aid lessons about animals and their habitats. E-mail to a friend
Gibbons, 54, was convicted for inciting religious hatred Thursday because she let her students name the cuddly toy Muhammad, which also happens to be the name of the Muslims' revered prophet. The offended believe Gibbons' intentionally slighted the prophet by greenlighting the name. She was sentenced to deportation and 15 days in jail for her "crime."
Gibbons' boss at the posh school thinks the verdict was fair because she could have gotten a half a year in the slammer and 40 stinging lashes.