Police allege that one of two Sydney men arrested today is the ringleader of a criminal syndicate which has been helping recruit people to travel to Syria to join the fight against the Assad regime.

The arrests, which the Australian Federal Police say are not related to any local terrorism threat, come after reports emerged that an Australian man had blown himself up in a suicide attack at a military airport in the east of Syria.

Hamdi Al Qudsi, 39, has been charged with seven offences, including being a conduit for people leaving Australia to fight in armed hostilities against the Syrian government.

Police allege five young men left Australia for that purpose between late June and July this year.

Al Qudsi appeared in Bankstown court this afternoon and was granted bail with very strict conditions, but will be held at Sydney's Silverwater jail until he can produce the $10,000 security required.

The second man, 23-year-old Amin Mohammmed, was arrested as he was due to board a plane from Brisbane airport to Syria, allegedly to help fight in the conflict.

He was also granted bail with strict conditions but remains in custody after failing to come up with the $5,000 bond.

AFP Deputy Commissioner Peter Drennan says the arrests were the result of a joint investigation between the AFP and NSW Police.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 11 seconds 4 m 11 s Arrested: Kingpin sending Australians to fight in Syria ( Martin Cuddihy ) Download 1.9 MB

"We will allege one of the men is responsible for arranging overseas contacts, facilitating travel into Syria for Australian citizens to fight on the front line," he said.

"Police will allege six people were facilitated into Syria and one was stopped by Australian authorities from leaving the country.

"Police also allege that the other male committed a number of acts to leave Australia and to travel to Syria to fight in armed hostilities."

He said the men were linked to a terror organisation Jabhat al-Nusra, which was affiliated Al Qaeda.

Joining Syrian rebels a criminal offence in Australia

Federal Attorney-General George Brandis says the arrests are a reminder of the risks to Australia's national security from people who support or engage in foreign conflicts.

Senator Brandis says the threat posed by Australian travellers to Syria and other conflict zones is "significant" and will likely have long-term implications for national security.

Deputy Commissioner Drennan said while he understood the desire for the Australians from within the Syrian community to act, joining the rebels was a criminal offence in Australia, irrespective of whether people were linking up with terrorist organisations.

"Jahbut al-Nusra has been prescribed by the Australian Government as a terrorist organisation," he said.

"Al Qaeda and its affiliates are also terrorist organisations.

"Travelling offshore to be involved in armed conflicts and facilitating travel for others to do this are criminal offences. The law in this area is quite clear.

"I realise the situation in Syria is an important issue for many people in our communities. There is no justification for violence.

"The fighting, killing of people, or people being killed shouldn't be glorified or justified for any reason.

"There are a number of alternative and lawful ways people in Australia can help through the United Nations agencies or nongovernment organisations such as Red Cross, Save the Children or World Food Program, who are providing assistance in and around Syria."

NSW Police's Deputy Commissioner, Catherine Burn, said she was confident the arrest will make it harder for people to travel to Syria to take up the fight.

"I think the critical aspect of this investigation is that we have identified who we believe is the principal person involved in the facilitation network of sending people over to Syria to engage in conflict," she said.

"That has taken some months to identify and I think that that will have put a significant dent into this particular network that is operating."

Four Australians have been killed in fighting in Syria

At least four Australians are known to have been killed in the fighting, and intelligence agencies are thought to be tracking about 100 Australians active in the Syrian conflict.

The conflict is a magnet for idealistic young Muslim men, looking to prove their commitment to their faith.

The Government is concerned some individuals will be further radicalised by their experiences overseas and could use their training to conduct terrorist operations upon returning to Australia.

In a report to Parliament last year, ASIO went as far as to warn that Australians fighting in Syria may return to "engage in terrorism", and it is thought that some of the Australians who have been killed have been fighting with Jahbat al-Nusra, a group with direct links to Al Qaeda.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 35 seconds 4 m 35 s Sydney men arrested for allegedly trying to join Syrian rebellion Download 2.1 MB

"Australians who are currently training or fighting overseas may also return to Australia to engage in terrorism, use their knowledge of Australia to help others plan an attack or engage in terrorism overseas," the report said.

However, Deputy Commissioner Drennan was quick to "reassure the Australian community that this is not about a terrorist attack here in Australia".

Most of the about 400 Australians currently involved in the Syrian conflict are thought to be working with the forces opposing the Assad regime.

Although some are actively engaged in the fighting, others are working as volunteers for humanitarian agencies and other Islamic groups.