Serial sex offender Phillip Clough was jailed for 3 years
Phillip Clough, 39, tried to persuade the 11-year-old victims to touch themselves in front of him.
The girls refused and fled but told police and Clough was arrested days after the offence last July.
Police raided his home in Derby and discovered 3,346 indecent images of children, aged between four and 13, on his phone.
Phillip Clough tried to persuade the 11-year-old victims to touch themselves in front of him
Clough, who has a string of convictions for sexual offences against children dating back to 2002, was already subject to an order banning him from entering parks.
I cannot believe he was allowed out to do it again
Mother of 11-year-old vitcim
Yesterday, he admitted possessing indecent images of children and two counts of causing a child to engage in sexual activity at Derby Crown Court.
Recorder Dean Kershaw said Clough was "a danger to children" and after he had served his prison sentence he would be on licence for a further four years.
Prosecutor Mark Knowles said: "He asked the girls to squat down and told them to open their legs wide and asked them to put their hands up their skirts and tops and rub about their tummy area.
Clough was previously convicted of possessing indecent images of children in 2009
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"They didn't and some other girls came over and he stopped and said sorry the magic hadn't worked and left the area."
The court heard Clough was a serial paedophile and was jailed for 15 months after he attracted the attention of youngsters before touching himself under his clothing.
He was also given a sexual offences prevention order and was put on the Sex Offenders' Register for ten years.
But by 2008 he had breached the conditions of the order and was given a three-year community order.
A year later he was back in court and jailed for four-and-a-half years after he was convicted of possessing indecent images of children and engaging in sexual activity in the presence of a child.
He was released in December 2010 and then five months later he went to a park in Mackworth, Derbyshire, where he made obscene suggestions to a five-year-old girl and was jailed for three years.
Justin Ablott, defending, said: "He wishes me to apologise to the court and those concerned.
"He was released from custody in 2013, so by the time these offences were committed he was back in the community for a not insignificant amount of time and was being monitored.
"And I have seen no evidence to suggest that he was anything but cooperative with that process."
Speaking after he was jailed for his latest crimes, the mother of one of the 11-year-old girls, said: "I'm glad he got a decent sentence.
"But I couldn't believe it when I heard in court about all those other offences he had committed before.
"I cannot believe he was allowed out to do it again."