An Oxford schoolboy was arrested and investigated for three months after creating spoof images of his teachers as Osama bin Laden and Shrek.

Louis Johnson, 13, a pupil at St Gregory the Great School, Cowley, had his mobile phone and his mum's computer seized in November and was locked in a cell for more than five hours.

He was eventually given a final reprimand on Wednesday, January 30, for harassment.

It came after the Government told police to crack down on 'cyberbullying' of teachers and pupils.

But Louis, of Campion Close in Greater Leys, said he did not distribute the pictures - showing faces of his teachers superimposed on to the bodies of Shrek and Osama bin Laden - and they were for his own amusement.

The images were first discovered by staff on a computer at Louis's school after an investigation was launched into pornographic material that had been downloaded.

Louis was not involved in downloading pornography, but he was warned about his spoof pictures at a meeting of teachers, his mother and schools officer Pc Brent Jacksonok.

But on November 21, Louis had his mobile phone confiscated at school and the same images were found again, prompting the school to call in the police again.

He was arrested and bailed and given a final reprimand, which stays on his record for five years, as the police looked into other allegations of harassment of teachers - allegations which were never put to Louis.

Mrs Johnson said: "This has put an awful lot of strain on Louis - he has even had to go and see a GP because the stress made him so ill.

"I feel this has all been rather pointless. Have the police got nothing better to do with their time?"

Louis has been made to attend a special youth offenders' team as part of his punishment.

He said: "I am so shocked by all of this. I only created the pictures because I was bored and I never showed them to anyone else.

"It was only meant as a bit of fun."

Police refused to say how many hours officers spent on the investigation or the number of officers involved.

They said Louis was held only in connection with this incident after "seven teachers said they felt the images were harassing and abusive towards them".

A police spokesman said: "Parents should be aware of what is on children's mobile phones, and making their children aware of the moral consequences of indecent images."

The school refused to comment.