The aunt of a missing 15-year-old schoolgirl who is thought to have been radicalised online before travelling to Syria says powerful jihadists are 'brainwashing' British teenagers through the internet.

Sucdi Ali said her family are 'heartbroken' over suggestions schoolgirl Yusra Hussien may have become a 'jihadi bride' after she secretly left her Bristol home more than two weeks ago.

She believes the teenager, who visited her in London over the summer, was radicalised online after spending increasing amounts of time on her laptop and smart phone and begged her to come home.

Scroll down for video

Yusra Hussien, 15, may have become a 'jihadi bride' after she secretly left her Bristol home and fled to Syria more than two weeks ago

'If she is in Syria, for her to become a thing, they say, Jihadi bride - if that is the thing Yusra did then internet grooming is definitely the case because where would this come from,' Ms Ali said.

'We don't want her to go to Syria and marry some unknown man, God knows who he is or what kind of guy he is or what kind of crime he's done or God knows what's in his head. It didn't come from us, where did it come from?

'We have to be all scared. If these powerful people are out there and they can brainwash these children or 15 or 19-year-olds to leave their own home then they are very powerful people.

'There will be more girls and boys leaving Britain or any other European country.'

Her aunt Sucdi Ali (left) said she believed the teenager was radicalised online after, pictured with mother Safiya Hussien, and Ikram Mohamed

Family believe she was groomed by powerful jihadists online after spending increasing amounts of time on her laptop and smart phone

On the day of her disappearance she told her family she was leaving early for a school trip but was not seen again.

'If it can happen to Yusra it can happen to anyone,' Ms Ali said.

'She was just a normal, young girl. She was a home girl.

'There was no anger, no frustration, no 'why is Syria going through this, why is this happening in Gaza?' We had no idea.'

Friends of Yusra claim to have spoken with her over the last few days via Facebook messages in which she said is 'safe and happy in her new life' but refused to say where she was.

Yusra, who is of Somali descent, is thought to have met up with 17-year-old girl Abdirashiid Dirie from London and headed to Turkey, where police believe they attempted to cross the border into the neighbouring war-torn state.

British authorities have expressed increasing concerns about hundreds of UK-born would-be jihadis who have gone to join Islamist forces in the Middle Eastern state.

Ms Ali added: 'We want her to know she hasn't done anything wrong. Wherever she is we love her still.

'She's not in any trouble. She won't be arrested. We just want her to come back to the UK.'

Her mother begged for her safe return after it was claimed that Yusra could have made contact with a dating site called Jihad Matchmaker.