A former hospital director has been convicted of trafficking a woman from Tanzania to Britain and using her as a "slave", in the first case of its kind to come before a court.

Southwark crown court heard that Mwanahamisi Mruke, 47, was brought to the UK by Saeeda Khan with the promise of a domestic service visa and 120,000 Tanzanian shillings a month (£50). There was also £10 a month pocket money. Desperate to fund her daughter Zakia's college education, Mruke agreed.

But when she arrived in Britain in October 2006, Mruke was forced by Khan to work around the clock and sleep on the kitchen floor of her home in Harrow, London, for the next three years.

Mruke was fed just two slices of bread a day, and ordered around by a bell, which her captor kept in her bedroom.

Although the payment arrangements were initially honoured, Khan stopped paying Mruke after one year. She was also prohibited from leaving the house, her passport was taken away, and Khan made threats about Mruke's relatives in Tanzania.

Yesterday the jury at Southwark crown court found Khan guilty of trafficking a person into the UK for exploitation. She was sentenced to nine months in prison, suspended for two years, and ordered to pay £15,000 towards police and prosecution costs, plus £25,000 compensation to Mruke.

Judge Geoffrey Rivlin QC said Khan had told "a pack of lies" during the trial. "Your behaviour was callous and greedy," he said.

During the trial, the jury was told that Mruke was forced to work between 6am and midnight each day. She was also woken during the night to take Khan's son for a walk and never received a day off.

When Mruke asked to go home after the deaths of her parents, and for her daughter's wedding, Khan refused.

It was only in February 2010, when Mruke visited her local doctor with an interpreter, Rhoda Mwanga, that concerns were raised about her living conditions. Mwanga contacted the charity Kalayaan, which seeks justice for migrant domestic workers, who alerted the police.

Ten days later police officers, accompanied by Mwanga and Kalayaan workers, visited Khan's home and rescued Mruke.

Khan, a widow, was arrested and later charged. Speaking after she was convicted, Mruke said she would "never forgive" the person who had imprisoned her.

"I felt like a fool, I was treated like a slave," she said. "Even the money I was promised, I was never paid. I feel terrible about this. "

Mruke said she had been hoped to "improve my life" in Britain. But her hopes had been "dashed, my strength was reduced and I became unwell."

She is now pursuing a civil claim against Khan.