A college lecturer who carried out spanking fantasies on his students was behind bars last night.

Terry Carroll, 46, pulled students over his knee and smacked their bottoms, telling them: 'You've been a bad girl.' The social care tutor also touched his victims' thighs while showing them how to log on to pornographic web sites without being caught.

A jury at Snaresbrook Crown Court in East London had earlier found him guilty of five counts of indecent assault, four relating to girls aged between 16 and 17 and a fifth to a student in her late 20's.

Sentencing Carroll to two and a half years in jail, Judge Nicholas Coleman told him: 'You were in a position of trust as a tutor and lecturer of your victims. You were employed as a college lecturer and you abused that trust.'

He said Carroll 'intimidated and preyed upon vulnerable students. . . fresh out of school.' He added: 'You threatened them with dismissal from the course if they did not work and implied if they did not submit to your demands they would be thrown off the course. You caused them a great deal of misery and a great deal of physical and mental pain.'

Carroll, a married man from Bishop's Stortford, Hertfordshire, was caught when an investigation was launched at the East London college where he taught following complaints of sexual harassment by students last year. The teacher, who had been in the profession for 15 years, was suspended and resigned a week later.

Outlining the abuse, which took place between October 1999 and February 2000, prosecutor Sheilagh Davies said: 'Clearly, Terry Carroll had a fixation with spanking.'

Carroll was sentenced to 30 months for each counts of indecent assault, to run concurrently but cleared of a further count of indecent assault and one count of common assault. He will be on the sex offenders' list when he is released.