He was found guilty of nine counts of causing a child to engage in sexual activity, three of sexual activity with a child and two of meeting a child following sexual grooming.

He was also convicted of one count each of rape, causing a child to watch a sexual act, and paying for the sexual services of a child at the trial, last month.

The convictions relate to 12 victims, and cover a two-year period.

Judge Jonathan Carroll handed the former Luton Constable a jail term of 15 years with an eight-year extended sentence.

This means he will be supervised by probation officer on his release until the year 2039.

Sentencing Arshad, Judge Jonathan Carroll told him: “Between 2009 and 2013 you actively and obsessively engaged in harvesting young 13 to 16 girls’ data from various social media sites.”

He said Arshad – who had lied about his age to the victims and later used his position as a police officer to impress his victims – was a dangerous offender.

Arshad, from Luton, Bedfordshire, was a trainee police officer between April 2014 and October 2014 but was suspended when one of the victims came forward.

Police who searched Arshad’s home found images of teenage girls on his phone and computers. Officers managed to trace a number of potential victims though social media messages.

Bedfordshire Police said they have reviewed their vetting process to prevent the likes of Arshad from joining the force again.