Gillian Gibbons, 54, of Liverpool, was found guilty of "insulting religion" after an eight-hour hearing in Khartoum north court. The maximum penalty she had faced was 40 lashes and six months in prison.

Ali Ageb, a member of Gibbons' defence team, said he was "very unhappy" with the verdict and would appeal. "She did this as part of her profession as the teacher," he told reporters outside the court. "She did not intend to insult anybody."

Ageb said Gibbons, who was arrested on Sunday, had been calm when the verdict was announced. "I think she was expecting it," he said.

Gibbons was sent to Omdurman women's prison, from where she will be deported after serving her sentence. She has served five days in jail, so should be eligible for release in 10 days' time.

The Foreign Office said it was "extremely disappointed" by the sentence, and David Miliband, the foreign secretary, again summoned the Sudanese ambassador to explain the verdict. During the 45-minute meeting, Miliband expressed concern at the continued detention of Gibbons "in the strongest terms". The Foreign Office said in a statement last night that there would be further contact today "in the search for a swift resolution of this issue".

Earlier, Miliband had told Omer Siddig of his "serious concerns" about the decision to charge Gibbons, calling the incident an "innocent misunderstanding". British Muslim groups had also called for her acquittal, saying the case was harming Islam's image.

Louise Ellman, MP for Liverpool Riverside, said the teacher's family were very upset. "I do realise that the sentence could have been harder, but 15 days in a jail in Sudan could be very, very harsh," she told Sky News. "There is still an appeals process ... the decision is one for the Sudanese authorities. I hope we can see some common sense here. I think there's distress and there's anger and I can't see much positive that has come from this."

It had emerged earlier in the day that complaints about naming the teddy bear Muhammad had come from a fellow member of staff at the exclusive Unity High School where Gibbons was working.

Teachers and clergy from the school's board turned up at court in support of Gibbons. Robert Boulos, the school's director, said education ministry officials had originally told him that a number of parents had laid complaints about the naming of the bear. But, he added: "Today I heard that it was a member of the school staff. I was horrified."

The complainant was named as Sara Khawad, an office assistant at the school, who was the key prosecution witness .

Gibbons had arrived at the modern marble-and-steel court in the Sudanese capital shortly before 1pm to answer charges of "insulting religion and inciting hatred".

Wearing a blue blazer, blouse and skirt, she appeared dejected and stared straight ahead as four policemen escorted her into the courtroom on the first floor, pushing through a throng of journalists, lawyers and supporters from the school.

Another group of policemen barricaded the door, shouting and waving angrily for people to move away. The prosecution team was already inside, but Gibbons' defence team was locked out.

British embassy representatives, including consul Russell Phillips, were also prevented from entering. A line of 15 police officers then formed a human chain, shoving the onlookers away. After a half-hour standoff, Kamal al-Jazouli, Gibbons' lawyer, pushed through the crowd and began shouting at the police. He was let in, but his assistants and embassy staff had to wait a further hour - during which time they witnessed two offenders being flogged with a rubber hose in the court corridor - before being admitted to hear the prosecution arguments.

The charges stem from a project initiated in September when Gibbons, who had been in Sudan for a month, asked pupils to suggest names for a bear, which each child would be able to take home and then write in a diary about their experience.

The chosen name was Muhammad, one of the most common names in Sudan, and also the name of Islam's Prophet. The diary featured a picture of a bear on the front and the label: "My name is Muhammad".

Since her arrest, there have been fears for Gibbons' safety, and that of her colleagues at Unity, which is now closed.

Riot police wearing helmets and shields and clutching batons and rifles were posted outside the court. But though leaflets condemning Gibbons had been distributed in Khartoum on Wednesday, there was no sign of protesters.

After the verdict, announced by judge Mohammed Youssef at 9pm, Boulos attempted to quell any lingering anger on the streets. "We are happy with the verdict," he said. "It is fair. There were a lot of political pressures and attention. We will be very sad to lose her."