Fears are growing for the safety of three east London schoolgirls who police believe are trying to cross the Turkish-Syrian border to join Islamic State (IS) extremists.

Shamima Begum, 15, Kadiza Sultana, 16 and their unnamed 15-year-old friend flew from Gatwick to Turkey on Tuesday.

Police have issued an urgent appeal for help in finding them, suggesting they are "extremely vulnerable".

The trio are friends with a fourth girl who travelled to Syria in December.

Muslim leaders have said they are "extremely concerned" for the girls, who attend attend Bethnal Green Academy.

'SERIOUS RAMIFICATIONS'

Worshippers at the East London Mosque were asked during Friday night prayers to come forward if they had any information to help the girls return home safely.

Mosque spokesman Salman Farsi said the trio, who have been described as "straight-A students", had been manipulated.

He said: "They have been misled. I do not know what was promised to them. It is just sad. We have not had anything like this before in our community.

"I do not know what was told to them but if they do go to Syria, it is a war zone and there are serious ramifications for going in to a war zone."

Rushanara Ali, MP for Bethnal Green and Bow, said there was "deep concern" and shock in the close-knit community.

Speaking on BBC Radio 4's Today programme about the possibility they were heading to Syria, she said: "We all of us hope that's not the case, but they left home without informing their families, left the country, which is extremely out of character so these are our worst fears."

She said advice and support was needed for schools and teachers concerned about any of their pupils.

"This is like grooming, this is child exploitation, and in the worst-case scenario they are potentially being used as weapons of war in those countries," the MP added.

'GRAVE DANGER'

Her concerns were echoed by Prime Minister David Cameron, who said the "fight against Islamist extremist terror is not just one that we can wage by the police and border control".

"It needs every school, every university, every college, every community to recognise they have a role to play.

"We all have a role to play in stopping people from having their minds poisoned by this appalling death cult."

Mussurut Zia, general secretary of the Muslim Women's Network, said the missing girls would not know what lay in store.

She told BBC Breakfast: "I don't think for one instant that these people, Isis [Islamic State] and their likes, are going to treat these girls in the right way.

"They won't have rights, they won't be equal to their male counterparts and I don't think that they know this at the moment and they're going to be in for a real shock."

She called for more training for airport staff to ask questions of those flying to border countries such as Turkey and raised the possibility of parental consent to be given when teenagers were travelling abroad alone.

Metropolitan Police Commander Richard Walton said he believed the girls would be "in grave danger" if they made it to Syria.

He said he hoped they would "hear our concerns for their safety and have the courage to return now, back to their families who are so worried about them".

Police hope the girls may still be in Turkey, as severe winter weather is currently affecting transport links in the country.

The three girls were last seen on Tuesday morning, when they told their parents they were going out for the day, police said.

CCTV at Gatwick airport captured the girls as they passed through security, before boarding a Turkish Airlines flight to Istanbul.

Shamima is possibly travelling under the name of her 17-year-old sister Aklima Begum, police said.

The third girl is not being named at the request of her family.

Abdul Samid, a parent governor at Bethnal Green Academy, said there was "absolutely not" any radicalisation at the school.

"I'm 100 percent confident - with the head and the senior leadership team and the whole school - that we've done everything to put in measures that safeguard all the children that attend the school," he said.

He said he did not believe the girls were trying to get to Syria.

"I still don't believe that they are going anywhere other than a holiday - because this is how they were dressed and this is how they looked and this is how they packed," he added.

Police have issued a description of the three girls:

Kadiza Sultana is 5ft 6in and slim build. She was wearing black-rimmed glasses, a long black jacket with a hood, a grey striped scarf, a grey jumper and dark red trousers and was carrying a black holdall. She speaks English with a London accent and Bengali

Shamima Begum is 5ft 7in. She was wearing black, thick-rimmed glasses, a black hijab, a light brown and black leopard-print scarf, a dark red jumper, black trousers and a jacket, and was carrying a dark blue holdall with white straps. She speaks English with a London accent and Bengali

The 15-year-old unnamed girl is 5ft 6in and slim build. She was wearing black, thick-rimmed glasses, a black headscarf, a long dark green jacket with a fur-lined hood, a light yellow long-sleeved top, black trousers and white trainers, and was carrying a black Nike holdall. She speaks English and Amharic

Shadow home secretary Yvette Cooper said: "The idea of 15-year-old British schoolgirls setting off to Syria is very disturbing, and shows that more action is urgently needed to stop young people being drawn into extremism and conflict, and to help families and communities who are trying to counteract extremist recruitment messages."

It is thought more than 50 British women have travelled to Syria via Turkey to join IS to become so-called "jihadi brides".