A police officer was blackmailed after he sought out a 13-year-old girl on the internet to send him revealing pictures of herself, a court heard.

The "girl" Douglas Bennett contacted turned out to be a man a judge called "a thoroughly objectional piece of work" who threatened to expose him.

The 50-year-old custody sergeant, who served for 23 years in Kent Police, agreed to buy his silence by sending him a £50 voucher for online shopping company Amazon.

But the police investigation into the blackmailer led officers to the door of married Bennett's home in Tilbury Road, Rainham. Computers were seized and child sex abuse images were found.

Now Bennett has been jailed for 16 months after admitting attempting to cause or incite child pornography and 15 offences of making indecent images of a child.

Maidstone Crown Court heard he had been dismissed from the police, he was being divorced by his second wife and his daughter had snubbed him.

Prosecutor Alistair Keith said the police investigation into the blackmailer was launched in North Yorkshire.

Bennett went into a chatroom in January 2010 and believed he was in conversation with a young girl calling herself Suzie Sue.

Chat logs revealed him asking for pictures of her in bra and panties and him saying he would like to see her on webcam showing her bra.

He asked: "You had sex before?" The reply was "No" and he then asked: "You want to?". He adds: "You got topless?"

"OK, ready for something to make your heart beat faster? You can stop and chat or I can report you to the police..." - what man posing as girl told Douglas Bennett

The contact eventually told him: "OK, ready for something to make your heart beat faster? You can stop and chat or I can report you to the police."

Bennett then apologised: "I am sorry for being a weak man. I won't do it again."

Asked what would happen if he was reported, he replied: "My family would shun me. My life as I know it would be over."

Claiming he worked in a bank, he said: "Yes, I would be finished. I would be unemployable. I feel sick because I am ashamed of what I have done."

Bennett was told if he sent the Amazon voucher he would not be reported.

Mr Keith said 280 indecent images were found on the computers, 27 of which were at the second highest level of four, 15 at level three, seven at level two and 231 at level one.

Judge Philip Statman told Danny Moore, defending: "He goes on the net with one intention. He wants to engage in conversation with a girl aged 13 and wants her to send a picture, and he gets unlucky.

"Instead of getting a child, he gets an adult who is prepared to blackmail him, but his intention was to be afforded that facility. We are dealing with an adult who is a thoroughly objectional piece of work from what I have been told."

He told Bennett, who went on to work for a double glazing firm: "You begged him not to report you because you knew what the consequences would be."

The judge said the most serious images downloaded were "sickening depictions of children abused by adults", each one of whom was a victim.

"The tragedy of your case is at the time you were committing these offences you were a serving police officer. You spent 23 years in the police force, rising to the rank of custody sergeant.

"As a result of these offences you have been dismissed. I well understand you have fallen, whatever the sentence of this court, a very, very long way.

"The impact on your private life is dramatic. Your second marriage has come to an end. Your daughter from your first marriage has disowned you and won’t allow you access to her child.

"But it is clear to me beyond doubt that those who go on the internet for such purposes will, and indeed must, be sent to prison."

Judge Statman said he hoped that if Bennett did not undergo sex offender treatment in prison he would do so on his release.