Family urges amnesty as anti-IS Australian arrives home

An Australian who joined Kurds battling the Islamic State group in Syria arrived home on Monday, as his parents called him "a hero" and pleaded with authorities not to charge him under foreign-fighter laws.

Ashley Dyball, 23, was detained in Germany while taking a break from a Kurdish military campaign against IS in northern Syria and was 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 (and) released without charge pending further inquiry".

Police said any Australian identified as a threat to security would be fully investigated, without specifying whether he would be charged.

"The public can rest assured that any Australian who is identified as a threat to security will be investigated by the relevant agencies," the federal police said in a statement.

"The safety of the community is the main priority of all Australian government agencies involved in this matter.

"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 traveling 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 in the conflict.

Canberra has introduced new laws to combat the threat, with foreign incursion offenses updated as part of new counterterrorism laws introduced last year aimed at blocking jihadists going overseas to fight.