The Sydney family of Mustafa al-Majzoub, centre, say he was killed while doing humanitarian work in Syria in August 2012. What they are fighting for is difficult to say - they are not joining the ranks of the more moderate Free Syrian Army, whose aim is to overthrow the regime of Bashar al-Assad. Instead, they are mostly here to sign up to the al-Qaeda-linked groups of Jabhat al-Nusra and the Islamic State of Iraq the Levant (ISIL), whose plan is to establish a transnational Islamic state beyond the current borders. The Australian Federal Police reports up to six Australians have died ''while fighting with al-Qaeda-affiliated terrorist groups in Syria''. The AFP says up to 100 Australians are still fighting inside Syria. Court documents name six: Tyler Casy (Abu Qaqa), Caner Temel (Abu Moussa), Mehmet Biber (Abu Abdul Malik), Muhammed Abdul-Karim Musleh (Abu Hassan), Mahmoud Abed Aboshi (Abu Alem) and Nassim Elbahsa. Among those known to have died in battle is 23-year-old Roger Abbas, from Melbourne, who reportedly went to Syria to do aid work, became involved with Jabhat al-Nusra and was killed in October 2012. The Sydney-based family of Mustafa al-Majzoub say he was killed while doing humanitarian work in Syria in August 2012. He was the first Australian to die in the bitter fight to overthrow the Assad regime.

Sources: International Centre for the Study of Radicalisation, Australian Federal Police. His brother, Sheikh Feda' al-Majzoub, has been a vice-president of the NSW branch of the National Imams Council and a member of the NSW Islamic Council. Allegations from the Assad regime, published this week in The Australian, claim Feda' al-Majzoub played a role in the kidnapping of 100 civilians during a massacre in the Latakia province of Syria last August. Fairfax Media has been unable to contact al-Majzoub regarding the allegations. However, a Human Rights Watch investigation into the massacre points the finger of blame at the more radical Islamist groups now dominating the opposition fighters - groups with which al-Majzoub is not known to have any association and of which he is highly and publicly critical. ''Five groups who were the key fund-raisers, organisers, planners and executors of the attacks were clearly present from the outset of the operation on August 4. These are Ahrar al-Sham, the Islamic State of Iraq and Sham, Jabhat al-Nusra, Jaish al-Muhajireen wal-Ansar and Suquor al-Izz,'' the Human Rights Watch report found.

The extent of the involvement of other groups such as the Free Syrian Army in abuses is not clear, nor is it clear whether they were even present on August 4 - the date when Human Rights Watch believes the abuses took place, the report says. Talking over tea and baklava in a cafe in Istanbul in December before the allegations against him surfaced, al-Majzoub is still clearly devastated by Mustafa's death more than a year before. He laments both the influx of foreign jihadists to Syria and their ideological influence over Syrians' fight for freedom. A foreign policy adviser to the secretary general of the opposition Syrian National Council, al-Majzoub describes the changes on the ground inside Syria in the past six months as ''dramatic''. ''The situation now is very different to what it was on March 18, 2011, when people were just demonstrating and seeking freedom, democracy and safety, to release those who are tortured and bring the torturers to justice,'' he says.

Referring to a radical Islamist element that has gained ground in Syria, he says: ''Those who came to Syria with their agenda, trying to use Syria as a base for their program, they are really placing us in a very, very tough position.'' So what does he say to those foreigners who want to show their solidarity or support for the Syrian people? ''We ask them please, you can support us without coming here.'' But once they do arrive in Syria - or in the towns along the Turkish border - it is the radical groups that are drawing in the most foreign fighters. ''I don't think their intention is to end up with the radical groups,'' al-Majzoub says. ''I think their intention initially was to defend, to help, to show their compassion to the Syrian people, but when they get in [to Syria] that is a different story. They end up with radical groups, some of them, that is the nature of the conflict at this stage.''

Added to this potent mix are the brutal acts of terror the Assad regime perpetrates against its own people, he says. ''The level of violence by the regime is placing no limits on those who would like to do something for the Syrians.'' The radical groups now dominating the battlefield inside Syria are trying to ''shape a new Syria'', he says. ''Now is not the time for it and we are not ready for it … the real challenge is to get rid of the Assad regime, that is our main purpose for the future of Syria. ''The confrontation between ideologies - that is too, too much for Syrians in the middle of this war to have to face.'' And with this dominance comes a real and growing threat that means the once open passage used by opposition representatives, journalists and humanitarian workers via southern Turkey is no longer viable.

Very few non-Syrian journalists are reporting on the conflict as so many have been kidnapped by ISIL or their related entities, while humanitarian work and the work of the Syrian National Council representatives such as al-Majzoub has been severely curtailed. ''In the past it was much, much safer, now it is not,'' he says. ''Even for me to go into Syria I have started to consider the security more than ever before.'' Several visits to this Kilis hotel and another known to house foreign fighters in Kilis turns up no Australians preparing to enter Syria. Instead, it is mostly filled with Syrians who, after enduring nearly three years of aerial bombardment, sniper fire, food, water and electricity shortages, have finally decided to flee to Turkey. The scene at the Kilis bus station is one of quiet desperation. Syrians too old and frail to be out in the snow are carrying huge, bulky packages on their shoulders or heads, filled with blankets or thin mattresses - the only defence from the cold they were able to transport across the border. Children, red-faced from the chill, trundle around in their boots and parkas like miniature Michelin men, while their mothers sit frozen in silence on benches. Some have no plans beyond their safe arrival in Turkey.

There are up to 10,000 Syrians in a camp for the internally displaced just across the border inside Syria, while the Turkish-run refugee camps in Kilis are so full they are turning people away. And with the first heavy snowfall of the winter, sleeping rough in a nearby park as so many families have been forced to do has become unbearable. Refugees are freezing to death on both sides of the border. It is into this vacuum of hope that many foreign fighters, including Australians, arrive. One Syrian activist now based in Turkey who has been tracking the arrival of foreign fighters, particularly those from Saudi Arabia, says the word went out about a month ago that flying from Istanbul to the smaller airports of Hatay or Gaziantap was no longer an option. ''They are too easy for the Turkish officials to spot, they stand out with their beards and their clothes,'' says the activist, who did not want to be named. ''So instead they make the 1200 kilometre journey by bus - sometimes it can take 17 hours.'' There are no Australians at the bus station during my visits, just a tiny smattering of Saudis and Azerbaijanis and a man from Central Asia.

Back at the hotel in Kilis, the workers have returned from their day earning a tiny wage and the lounge room gradually fills with men drinking tea, smoking and talking quietly. Twenty-four-year-old Mahmoud left Aleppo city a year ago and now works in the hotel. ''I have seen foreign fighters for ISIS [ISIL] and foreign aid workers who are also with ISIS - they come here to this hotel and they go into Syria. ''Sometimes they come every day, sometimes every week, mostly from Libya, Tunisia and Chechnya,'' he says. But, he says, he has not seen Australian fighters recently, only those who go into Syria to distribute aid. ''I met some Australians of Lebanese origin who came here to distribute aid,'' Mahmoud says. One man, Abdullah, was about 40 years old and did not speak Arabic very well, he said. ''It was not his first visit, he has gone many times to Syria since last winter,'' Mahmoud says.

''He would go to Gaziantap [a city one hour away] and buy clothes to distribute in the camps inside Syria, just near Azzaz, about 10 kilometres in from the border, to the people who have been displaced by the war.'' He was not a fighter, Mahmoud insists. ''How do I know this? I saw a picture of him holding a gun but it was taken inside a house and he was wearing nice clothes, city clothes, not soldier clothes. ''He talked about going to the hospitals to help the sick and injured, he never spoke about fighting. He went back to Australia maybe three weeks ago.'' Mahmoud named another man, Zakaria, who he described as a 23-year-old Lebanese-Australian. He was arrested in the Salah-ah-Din district of Aleppo by the regime and imprisoned for one year, he said. ''I met him here at the hotel.'' A Syrian rebel, Abu Khaled, who has rejected the FSA for a more Islamist brigade, recalls another Australian fighter who trained as a sniper at a Jabhat al-Nusra camp in Hasaka city in July.

He remembers the man - who he will not name - did not speak much Arabic but was good in a crisis. ''He was arrested by the YPG/PKK [Kurdish militia] and yet he managed to speak to them and convince them he was not in Syria to fight the Kurds, he was there to fight Assad, and they let him go,'' says Abu Khaled, a former military commander with Jabhat al-Nusra. ''He was brave - he did not get a chance to finish his training as the fighting was very bad and we needed to send him to battle.'' Charles Lister, a visiting fellow at the Brookings Doha Centre and an expert on jihadist movements, says the rate of foreign fighters infiltrating northern Syria via southern Turkey has spiked since the chemical weapons attack in August in which at least 800 people died. There are now believed to be up to 11,000 fighters from 74 countries, according to the latest figures from the International Centre for the Study of Radicalisation released in December.

The big question, says Lister, is why so many foreign fighters are attracted to the battleground of Syria. ''In terms of Australia, you are travelling halfway across the world to get there [and] to travel across half the world to fight in Syria it really does emphasise the emotional pull that the jihad in Syria is exerting now. ''The ease with which one can enter Syria has a very significant part to play in the attraction of fighting there - certainly it is far more difficult to enter to fight in Pakistan or even in Iraq and certainly it was difficult in the Afghan jihad. ''It is also about how comparatively easy a life you can have once you get in - the sheer extent of 'liberated territory' in Syria means that … you are not going to have the struggling life that you might have if you chose to travel to Afghanistan or Pakistan.'' Then there is the religious significance of Syria - the idea of Bilad al-Sham or greater Syria, a caliphate that encompasses much of today's Iraq, Syria and Jordan, Lister says.

The ready access to imagery of the extent of human suffering going on inside Syria is also key to the recruitment of foreign fighters, he says, as is the overt sectarian element to the conflict and the very clear role Hezbollah and the Shiite militias are playing to support Assad. To a foreign jihadist, when you add these elements together ''it appears an entirely just war in order to stop human suffering and fight against your real religious enemy''. It is the perfect storm.