Now one of them is believed dead - but which one is not yet confirmed

Last week, two other girls of the same age caught attempting to flee country

Pair began to post pictures of themselves online with guns and armed men

One of two Austrian teenage 'postergirls' who flew to Syria in April to join Islamic State ranks is believed to have been killed.

Samra Kesinovic, 16, and her friend Sabina Selimovic, 15, vanished from their Vienna homes earlier this year.

Soon afterwards they posted images of themselves branding Kalashnikov rifles, surrounded by armed men - photos which Austrian police feared were acting as militant recruitment posters for young girls.

Left is Samra Kesinovic, 16, who is thought to have fled to Syria to join the Islamic State. On the right is 15-year-old Sabina Selimovic who went with her - it is believed one of the girls is now dead

Samra Kesinovic and Sabina Selimovic in a photo they posted online. Last week, police expressed their fears that the two were inspiring other girls to flee to Syria to take up holy war

It is not yet known which one of the teenagers has been killed as the death is yet to be officially confirmed by the Austrian government.

Alexander Marakovits, spokesperson for the Interior Ministry, told The Salzburger News: 'We also have this information and have checked it, but cannot say with absolute certainty that it is true.

'But the parents have been informed their daughter could be dead.'

Konrad Kogler, Director General for Public Security, also confirmed there were unverified rumours of the death on Sunday evening's ORF program 'In the Centre', The Local reports.

The motivations of the two Bosnian girls are unclear but before leaving, they had contact with Chechen youths, and visited a mosque in Vienna's second district.

And last week, police expressed concerns that the pair were inspiring their contemporaries after two other teenage girls were caught attempting to flee the country to join IS ranks

Samra Kesinovic and Sabina Selimovic in another photo they posted online, sometime after they fled Austria

Austrian media warned several weeks ago that the girls had become the public face for the call to jihad.

The fears appeared to be validated with the Austrian Interior Ministry confirming two other girls from Vienna had attempted to flee to take up the call for holy war.

Little information was given about the latest pair hoping to join Islamic State apart from the fact that one was 16 and the other was 14 and their parents were apparently from Iraq.

Police now want to find out how they became radicalised, and whether anybody had helped them plan their trip to Syria which was apparently set to take place via Turkey - following the same route as the other two girls.

The pair were caught when the mother of a third friend who was supposed to be travelling with them became suspicious about the amount of luggage her daughter was packing.

Sabina, pictured beside jihadists wielding Kalashnikov rifles, somewhere in Syria or Iraq

It's not known if they group were in contact with Samra and Selimovic, who - despite the fact they are being hunted by Interpol - have remained missing.

However, social media updates posted by the two show them dressed in traditional Muslim clothing and in some instances, standing beside men holding guns.

As many as 130 people from Austria are now believed to be fighting as jihadists abroad.

More than half of Austrian's jihadists originally come from the Caucasus region and have a valid residence permit in Austria.

Meanwhile, two Salafists were intercepted in a German border town on the way to Syria via Austria.

Austrian Interior Ministry spokesman Alexander Marakovits said they were noticing an increasing problem with youngsters wanting to leave the country for the same reason.

He said: 'If we can catch them before they leave we have the chance to work with their parents and other institutions to bring the youngsters out of the sphere of influence that prompted them to act in this way the first place.