An Australian activist with first-hand experience of the horrors of the Syrian civil war is warning fellow Australians against travelling to the country, whatever their motivations.

Brisbane man Yehya El-Kholed, who recently returned from his third trip in two years to the war-torn country, has close family ties in Syria and Lebanon, and supports the overthrow of the regime of Bashar al-Assad.

But relentless bloodshed, daily air raids on civilian areas around Aleppo and, most significantly, the descent into chaos and infighting by anti-Assad forces, have left him disillusioned.

"My advice to Australians is do not go to Syria ... because you're going to get killed," he said.

"They're killing Westerners. Free Syrian Army will kill them thinking they're ISIS (Islamic State of Iraq and the Levant), and ISIS will kill them thinking they're Free Syrian Army.

"If you take a side you'll be killed, and if you don't take a side you'll be killed."

His most recent trip, at the end of last year, went ahead despite a last-ditch attempt by community leaders and the Australian Federal Police to persuade him to stay at home.

Mr El-Kholed took money he raised in Australia for humanitarian aid, which he says he distributed to families affected by the conflict.

He said he came across only "a couple" of Australians in Syria but "thousands" of foreign fighters, mostly from Egypt, Libya, Tunisia, and France and a few from the UK.

"It's like the whole world is in Syria," he said.

He also spent time with militants including Free Syrian Army fighters and members of Islamist rebel group the Tawhid brigade.

People planning to go to Syria even for humanitarian reasons should think twice, he said, with so many refugees having fled to neighbouring countries, there was more that could be done outside Syria.

"If you want to help out, go to Jordan because our sisters are being sold to prostitution (there)."

'I just saw Muslims killing Muslims'

He also warned of the risks for well-meaning foreigners of becoming desensitised and sucked into bloody factional battles that were only worsening the conflict.

Mr El-Kholed said he was not against people waging "jihad" against the Assad regime, but he would not encourage it.

"I just saw it was Muslims killing Muslims, and people killing civilians," he said.

"You see these videos ... (men) looking like mujahideen... thugs who converted to Islam who've got violence within themselves. They're just there for their own violent fetish."

Mr El-Kholed said he had witnessed first-hand how a popular uprising had transformed into bloody civil war and Islamist groups begin to fill the political vacuum.

"You had a revolution that came out for democracy, (and) they got butchered by the (Assad) government.

"The world which loved democracy did nothing about it (and Al Qaeda-linked group) Jabhat al Nusra started defending them.

"No-one from outside came to defend them and this touched their hearts.

"So the hearts of the Syrians have now moved away from democracy and to sharia - which in some areas is working really well."

More arrests predicted in relation to recruitment of fighters

Since his return at Christmas, Mr El-Kholed said he had heard news almost daily of friends being killed in factional infighting or dying of their wounds in neighbouring Turkey.

His comments came as the Australian Federal Police predicted more arrests in relation to the recruitment of people to fight in Syria, a serious crime under Australian law.

AFP counter-terrorism chief Neil Gaughan told the ABC there were probes under way in Queensland, New South Wales and Victoria.

It follows the arrest of Sydney man Hamdi Al-Qudsi, who has been charged with sending six young Australians to fight in Syria, including two who were killed in rebel infighting earlier this month.

"The arrest in Sydney in December did smash one cell ... but we have not stopped the problem," Mr Gaughan said.

"People continue to travel."

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