Users of geosocial dating apps such as Grindr have been warned by the National Crime Agency (NCA) to ensure that sexual partners are above the age of consent.

The warning came after an NSPCC report noted an increase in the number of teenagers calling in following bad experiences using such apps.

The charity said that it did not have specific figures on dating apps, however 1,061 people had called its switchboards after experiencing online sexual abuse.

The report specifically noted “geosocial” apps as the most easy to abuse.

Some users told the BBC that that they had lied to sign up to such apps when coming to terms with their sexuality, but later felt that they had been “groomed” by older users.

Jonathan Baggaley, head of education at the NCA said: “Just because we’ve not received huge reports doesn’t mean this isn’t a major issue. Clearly the very dynamic of this kind of relationship means young people won’t report it.”

“The law is very clear: regardless of how the conversation is started, regardless of who thinks they’re in the driving seat the adult is always the one who has the responsibility. A child should never be blamed.”

NSPCC spokeswoman Claire Lilley said: “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.”

Blendr – which also owns Grindr said in a statement: “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.”

Despite this, however, it is still possible for under age users to lie about their age when using the apps.

The Department for Culture, Media and Sport told the BBC that terms of use and age restrictions had been added voluntarily by app developers, but that they did not stand up in law, and were not legally enforcible.