Sydney: An Australian who joined Kurds battling the Islamic State group in Syria arrived back home Monday with his parents pleading with authorities not to charge him under foreign fighter laws, calling him "a hero".
Ashley Dyball, 23, was detained in Germany while taking a break from a Kurdish military campaign against IS in northern Syria and deported on Saturday night.
He touched down in Melbourne and was questioned by Federal Police officers for several hours before being allowed to travel on to Brisbane, where he is from.
His lawyer Jessie Smith told reporters in Melbourne he was "interviewed, released without charge pending further enquiry".
Police said any Australian identified as a threat to security would be fully investigated, without specifying whether charges would be laid.
"The public can rest assured that any Australian who is identified as a threat to security will be investigated by the relevant agencies," federal police said in a statement.
"Australians have been consistently warned that by becoming involved in overseas conflict they are putting their own lives in mortal danger," it added.
Australian officials have been increasingly concerned about citizens travelling to Iraq and Syria to join extremist groups such as IS, with some 110 Australians currently fighting in the region. As many as 45 have died.
Canberra has introduced new laws to combat the threat, with foreign incursions offences updated as part of new counter-terrorism laws introduced last year aimed at blocking jihadists going overseas to fight.