KHARTOUM, Sudan (CNN) -- Hundreds of angry protesters, some waving ceremonial swords from trucks equipped with loud speakers, gathered Friday outside the presidential palace to denounce a teacher whose class named a teddy bear "Mohammed" -- some calling for her execution.

An undated amateur photo of Gillian Gibbons, who has been found guilty of insulting religion.

The protesters, which witnesses said numbered close to 1,000, swore to fight in the name of their prophet.

Gillian Gibbons, 54, was given 15 days in jail late Thursday after she was convicted of insulting religion. She was cleared of charges of inciting hatred and showing contempt for religious beliefs, her lawyer, Ali Ajeb, said.

Ajeb said they planned to appeal the sentence, which begins from the date she was detained, Nov. 25. Including Friday, she has 10 more days in jail.

British Foreign Secretary David Miliband said he was "extremely disappointed" that the charges were not dismissed.

Meanwhile senior British lawmakers were en route to Khartoum to try to secure Gibbons' early release.

The two members of the House of Lords were set to arrive in Khartoum about 5 a.m. Saturday (9 p.m. Friday ET), Time magazine reporter Sam Dealey told CNN, citing British and Sudanese sources.

They will meet with government ministers and Sudanese President Omar al-Bashir, he said.

Sources close to the British government and the Republican Palace in Sudan say it is expected that a deal will be reached, and Gibbons will be released, Dealey said. Visas for the two, he said, were granted "in record time ... by Sudanese standards."

Friday's demonstrations began as worshippers spilled out of mosques in the capital after Friday prayers. They marched to the palace, which is on the same street as Unity High School, where Gibbons taught grade school students. Those who named the bear were 7 years old.

A heavy police presence was maintained outside the school, but no demonstrators were there. Watch men brandish knives, shout »

Armed with swords and sticks, the protesters shouted: "By soul, by blood, I will fight for the Prophet Mohammad."

Western journalists who attempted to talk to the protesters were ushered away by men in plain clothes. Gibbons is being held in a women's prison in the Omdurman district of Khartoum, and she will be deported at the end of her prison term, British consular officials told CNN.

British Embassy staff said they were giving the teacher -- from the northern British city of Liverpool -- full consular assistance.

In leaflets distributed earlier this week by Muslim groups, the protesters promised a "popular release of anger" at Friday's protests.

The leaflets condemned Gibbons as an "infidel" and accused her of "the pollution of children's mentality" by her actions.

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 to name the stuffed animal 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 received a sentence of 40 lashes, a fine or jail term of up to a year, according to the Foreign Office.

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. Watch a report on reactions to the verdict »

In an editorial, the tabloid newspaper, The Sun, said Gibbons' jailing was a "grotesque insult to Islam" and called Gibbons "an innocent abroad."

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Four vans filled with riot police were waiting outside the courthouse at Thursday's hearing, but there were no disturbances. Staff from Gibbons' school, including director Robert Boulos, were present.

Defense counsel later confirmed that the complaint against Gibbons 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

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