Among the brides who have travelled to Syria to join the jihadi cause is Salma Halane, 16, from Chortle, Manchester

An ever-growing band of young women have left their families in Britain to join the jihadi cause in Syria.

Researchers have identified six more such women through their online accounts – and warn this could be the tip of the iceberg.

Many have formed ‘intense friendships’ in the Islamic State stronghold of Raqqa, where they appear as content shopping with friends as declaring their hatred of the UK.

Academics at King’s College in London said they have seen ‘a big uptake’ in the number of UK women going to Syria.

Among them are Salma and Zahra Halane, 16, twins from Chorlton, Manchester, and mother-of-one Khadijah Dare, 22, who is married to a Swedish jihadist.

Privately educated radiography student Aqsa Mahmood, 20, from Glasgow, made headline news this week after her sobbing middle-class parents begged her to return.

Mahmood even compiled an online ‘Diary of Muhajirah’, advising would-be brides to ‘bring make-up and jewellery from the West because please trust me there is absolutely nothing here – unless you plan on looking like a clown.’ The rise in female recruitment comes as it emerged British jihadis in Syria have contacted the UK pleading to return home without being imprisoned.

As many as 600 Britons are believed to have joined Islamic forces fighting President Bashar Assad in the last three years. But many have become disillusioned with the brutal IS regime and associated groups.

Prime Minister David Cameron has vowed to ban British fanatics fighting in Iraq and Syria from re-entering the UK. However, one jihadist who represents up to 30 Britons has already approached an intermediary about the possibility of returning without the threat of prosecution, insisting they pose no risk to the UK. He said they were willing to enter de-radicalisation programmes.

Intelligence officials said last night they were aware some fighters were investigating ways of returning to Britain.

But one Syrian anti-terror expert warned: ‘You only need one to be wrong. Where do you draw the lines between the groups?’