Authorities at Sydney Airport have intercepted potentially the single largest group of suspected Australian jihadists to ever attempt to travel to a Middle East war zone.

The group of five men carrying thousands of dollars in cash allegedly planned to fly to Syria and Iraq, an intelligence source told News Corp.

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It is understood the men were “red flagged” at the immigration checkpoint at Sydney, where counterterrorism forces apprehended the group.

Immigration and Border Protection Minister Peter Dutton refused to comment. Photo: Getty

They had tried to board a flight to Malaysia with at least $9,900 cash each.

One of the men allegedly carried $12,000 in cash. The limit before cash needs to be declared is $10,000.

It is believed the cash was what flagged the interceptions. The men were known to authorities.

All the men had their passports suspended immediately. The attempt occurred last week, August 12.

Remarkably, reports said two of the men tried to escape the country again the next day.

“They triggered an alert when they tried to leave,” the source told News Corp.

“Then the CT [counter-terrorism] guys were called in to look at them and they were offloaded. It’s certainly one of the larger, if not the largest group trying to get over there.”

Minister for Immigration and Border Protection Peter Dutton refused to confirm the interception.

Reports said that the Australian jihadi death toll in the Middle East had risen to 39.