A SEX offender caught with a mobile phone in his cell has been handed more time behind bars.

Joseph Mills, 29, had already admitted one count of having without authority a mobile phone at HMP Bullingdon.

Oxford Crown Court heard at his sentencing hearing yesterday how Mills was caught during a cell search on the morning of June 26.

READ ALSO: Police hunt for two men after fuel stolen from Abingdon.

Prosecutors said at the hearing that on closer inspection a mobile phone was seized from inside a drawer.

Officers also found a USB charging cable.

A victim personal statement was also read out from the prison's head of security.

In that statement he derided the 'undermining' effect phones in prison have on the good order and discipline inside.

The court heard yesterday how Mills is currently serving a 12-year sentence imposed for sexual assault and other assault offences.

He also has a number of previous convictions made up of 13 convictions for 22 offences.

READ ALSO: Rate of Oxfordshire pupils struggling with mental health tops national average.

Defence barrister Peter Du Feu, representing Mills, said that his client had used the phone to contact friends and family and described the offence as a 'blip'.

He added that Mills was a 'good prisoner' who fell to the 'temptation' of having his own phone, and that he accepted his guilt.

Sentencing, Judge Peter Ross said: "You are a man who is used to the prison estate, is used to the rules of our prisons.

"You are a man who is well aware of the prohibition in relation to mobile phones and the consequences that follow from that.

"In your case it would appear that the use of a phone was limited to people in respect of whom you were permitted to mark contact."

Mills was jailed for six months.