'Come home. We miss you. We can't stop crying'

British schoolgirls (from left) Kadiza Sultana, Amira Abase and Shamima Begum are believed to be in Syria.

Families of Isis schoolgirls beg them not to flee to Syria

The father of one of three schoolgirls who are believed to have travelled to Syria to join Isis has appealed for her to come home, saying her younger brother and sister "cannot stop crying".

Abase Hussen, whose daughter Amira left the UK last week on a flight to Turkey along with Shamima Begum, 15, Kadiza Sultana, 16 - all of whom could have already cross the border with Syria - said she told the family that she was going to a wedding.

"We are depressed, and it's very stressful," he told Sky News. "The message we have for Amira is to get back home. We miss you. We cannot stop crying. Please think twice. Don't go to Syria."

His appeal came after Commons Leader William Hague called for new powers to intercept online messages to prevent more Britons travelling to join the militant group that has taken over large swathes of Syria and Iraq and has shocked the world with brutal videos of murders.

"You are looking for needles in haystacks," he told the BBC. "What's remarkable is how often we do find the needle in the haystack." He added: "In order to continue to do that in the future we will need to update the powers of the security services as technology is changing all the time and that makes it harder to intercept organised crime or potential terrorist activity."

Kadiza Sultana's older sister, Halima Ms Khanom, and one of Shamima Begum's sisters, Renu, also urged their siblings to get in touch.

"Find the courage in your heart to contact us and let us know that you're safe and you're OK - that's all we ask," said Ms Khanom, while Ms Begum added that nobody could love her sister more than they could.

Ms Begum said of her sister: "We love her, she's our baby. She's a sensible girl. We're hoping she wouldn't do anything that would put her in any danger. We want her and her friends to be safe. We want them to come home."

Ms Begum said her mother, who shares a bed with Shamima, was "not doing well". "It's left a big hole in the house," she said.

"Her family love her more than anybody else in this world can. If anyone is telling her they're going to love her more than us, they're wrong."

Police said the girls had been interviewed after another girl from their school went to Syria in December, but nothing had indicated they were at risk.

However, the family of Aqsa Mahmood, 20, who travelled to Syria to marry an Isis fighter and become a so-called "jihadi bride" in 2013 said that the security services had "serious questions to answer" over the way the three teenagers had been able to fly to Turkey without being stopped.

The family spoke out after it appeared that at least one of the three girls had been in contact with a relative on Twitter, before they flew from the UK to the Turkish capital Istanbul on Tuesday.

The Mahmood family said on Saturday that despite UK Government "rhetoric" about Isis, authorities had not taken "basic steps to stop children leaving" to join the militants.

However, Mr Hague said it was unrealistic to expect the security services to find every single thing posted online.

"Remember we've spent the past couple of years being heavily crit-icised for having so much surveillance," he said, adding that this was a good example of why it is necessary to intercept communications."

Parents, along with mosques and religious leaders, also had a "big responsibility" to stop their children going to Syria, he said, adding that it was "entirely open to parents" if they wanted to confiscate their children's passports.