Ahmad Mohamad al-Ghaz’zaoui, who had been fighting for the Islamic State group in Syria, was killed by soldiers of the Syrian army during fighting last week, according to media reports that cited a post by Syria 24 -- a pro-Assad Syrian social networking site. Al-Ghaz’zaoui had reportedly arrived in Syria from Turkey late in November.

“He would have been killed on the 25th or 26th of December … We are trying to contact the family but they are not answering,” Jamal Daoud, a Sydney-based activist, told the Australian Associated Press (AAP) on Tuesday, adding that al-Ghaz'zaoui's death had first been announced by a close relative.

Daoud reportedly added that al-Ghaz’zaoui was born in Australia but his family was originally from a small village in Lebanon. According AAP, he was hailed as a martyr by his friends and family after reports of his death emerged.  

Reacting to the reports, Australian Foreign Minister Julie Bishop said that Australian citizens heading overseas to conflict zones in Iraq and Syria was a matter of great concern.

“The fact that some of these people are leaving Australia and are not even under surveillance or of interest to our security agencies is, of course, deeply concerning,” Bishop said, according to media reports.

She also said that online posts that referred to al-Ghaz’zaoui as a martyr were “idiotic.”

“If people want to put stupid or idiotic things on Facebook, then that’s not an offence in itself. But if people are inciting or advocating or promoting terrorism under the new laws that this government has introduced, then that can be an offence,” Bishop reportedly said.

According to unconfirmed reports, at least three other Australian ISIS fighters, including one person accused of being behind a foiled plot to behead Australian citizens on the streets of Sydney and Brisbane, are believed to have been killed since October. According to estimates by the Australian government, at least 70 Australian nationals have joined ISIS in Iraq and Syria so far.

“We know there are some young Australians who think they’ve made the right choice in becoming involved in overseas conflicts, but that choice only adds to the suffering in Syria and Iraq and it’s putting those young Australians themselves and others in mortal danger,” a spokesperson for the Australian Attorney General’s Office reportedly said on Tuesday, urging people fighting for ISIS to leave the conflict zone, or risk facing arrest and prosecution on their return.