Ex Sydney youth worker 'killed in Syria'

A former Sydney youth worker is the latest Australian believed to have been killed in the conflict in Syria.

Shareef Alnimer from Campbelltown, in the city's southwest, was working in Syria for German Islamic charity Helfen in Not, which translates to "Helping in Emergency".

The 27-year-old is believed to have died in the past few days, according to ABC News.

The Department of Foreign Affairs and Trade has been unable to confirm the death because of the "extremely dangerous security situation" in the country which is wracked by civil war and the advance of Islamic State extremists.

"Australians who become involved in overseas conflicts are putting their own lives in mortal danger," a DFAT spokeswoman told AAP on Thursday.

"Any Australians fighting with non-state militia in Syria or Iraq should end their involvement in the conflict now and leave the conflict zone."