KHARTOUM, Sudan (CNN) -- A Sudanese court found a British teacher guilty of insulting religion and sentenced her to 15 days in prison Thursday for allowing a teddy bear to be named "Mohammed," British authorities and her lawyer reported.

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

Gillian Gibbons also faces deportation from Sudan after her prison term, her lawyer told CNN.

He said that he was "very disappointed" with the verdict and that Gibbons planned to appeal.

Gibbons was not convicted of two other charges brought against her -- inciting hatred and showing contempt for religious beliefs, her lawyer said.

Gibbons, 54, was arrested Sunday after she asked her class of 7-year-olds in Khartoum to name the stuffed animal as part of a school project, the British Foreign Office said. She had faced charges under Article 125 of Sudan's constitution, the law relating to insulting religion and inciting hatred.

Although there is no ban in the Quran on images of Allah or the Prophet Mohammed, Islam's founder, likenesses are considered highly offensive by Muslims. Watch latest developments in the case. »

Appearing somber and dazed, Gibbons arrived at the central courthouse in Khartoum for her closed hearing early Thursday. A staff member from the British Embassy in Khartoum and defense lawyers attended the hearing with her.

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The courthouse was heavily guarded by police, who kept journalists -- and, for a while, even one of her attorneys -- away.

Gibbons could have faced a sentence of 40 lashes, a fine, or a jail term of up to a year, according to the Foreign Office, which expressed Britain's dissatisfaction with the verdict.

"We are extremely disappointed that the charges against Gillian Gibbons were not dismissed," Foreign Secretary David Miliband said in a statement issued shortly after the verdict was announced.

"As I said this morning, our clear view is that this is an innocent misunderstanding by a dedicated teacher. Our priority now is to ensure Ms. Gibbons' welfare, and we will continue to provide consular assistance to her. I have called in the Sudanese ambassador, Omer Siddig, this evening to explain the decision and discuss next steps." Watch a report on reactions to the verdict »

The Foreign Office said Gibbons would be given credit for the four days since her arrest, meaning that the she has 11 days remaining on her sentence.

Earlier, Miliband had met with Siddig, who was summoned to the Foreign Office in London.

"I explained to him that we were very concerned by the case. We believe that this was an innocent misunderstanding," Miliband said in a statement released Thursday after the meeting.

"The Sudanese ambassador undertook to ensure our concerns were relayed to Khartoum at the highest level. He also said he would reflect back to Khartoum the real respect for the Islamic religion in this country," the statement added.

On the first floor of the courthouse, around 25 police linked arms and forced journalists and British officials away from the court entrance. Police detained some journalists, and confiscated a camera belonging to a freelance CNN cameraman.

Four vans filled with riot police were waiting outside the courthouse, 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. The staff members refused to comment on their colleague's predicament.

On Wednesday, Boulos said he was "horrified" when he found out that the complaint about the naming of the bear came from a member of his own staff -- not from 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, England, 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

Journalist Andrew Heavens contributed to this report.

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