Gay men who are using hook up apps like Grindr are being warned to ensure their sex partners are over 18.
The UK’s National Crime Agency has said, after an increase of teens reporting abuse on these apps, the responsibility is always on the adult.
If an adult receives a picture of someone under the age of 18, under the law it means they have indecent images of children.
And if an adult has sex with someone under the age of consent of 16, then they are breaking the law.
Speaking to Gay Star News, a spokesman said: ‘No matter what age you are, if you’re in any doubt of your partner’s age – just don’t do it.
‘The key thing is, we recognize people will use these sites to explore their sexuality. But if you’re feeling uncomfortable and questioning the age of someone else, don’t get involved.
They added: ‘When teens are using these apps, they might not always realize how they’re being exploited.
‘But the responsibility always rests with the adult. If doesn’t matter if the adult is 19 or 90, the responsibility lies with them.’
It follows a reported rise in the number of teens phoning the National Society for the Prevention of Cruelty to Children (NSPCC) helpline with bad experiences after downloading hook-up apps.
While gay men are not being directly warned, it is being noted teens are more likely to be using these apps for same-sex experiences.
The NSPCC said while they did not have specific figures on hookup apps, it had seen a rise in calls about them.
In 2012-13, over a thousand young people contacted its ChildLine to talk about online sexual abuse.
Claire Lilley, from the NSPCC, told the BBC: ‘These apps do have terms and conditions in place but they're simply not being enforced and as a result children are being put at risk of serious harm.
‘We know this because of the huge increase in calls to ChildLine over the last year about issues such as online grooming.’
While the age of consent in the UK is 16, the majority of hook-up apps’ terms of conditions insist users are 18 or over.
Jonathan Baggaley, head of education at the National Crime Agency, said: ‘‘Using mobile technology to communicate is a part of evreryday life particularly for children and young people.
‘That makes social and mobile media attractive to predatory adults with a sexual interest in children.
‘Contact from predatory offenders is not always obvious and children may not recognize that they are being sexually exploited.
He warned: ‘That’s why the law is very clear no matter how the exploitation happens responsibility always rests with the adult.
‘Adults should always be cautious and having sex with someone you believe is under the age of consent is illegal full stop. The child can never be blamed.’
In a statement, a Grindr spokesman said: ‘We do our best to ensure all users follow our strict terms-of-service policy that require users to be at a minimum age of 18.
‘We have a diligent team of moderators focused on monitoring and ensuring users adhere to our terms-of-service guidelines.’