Reports that young Australian women are travelling to the Middle East to fight with Islamic extremists are deeply concerning, Foreign Minister Julie Bishop says.

Intelligence agencies believe a teenager and her 20-year-old friend have become the first Australian women to go it alone to join Islamic State terrorists in Syria and offer themselves as potential jihadi brides.

The pair, aged 18 and 20, are believed to have links with the Somali community and flew out of Sydney in the past fortnight after lying to their families about why they were travelling, News Corp Australia reported.

While there have been cases of women joining husbands or boyfriends in the Syrian war zone, this is believed to be the first case of young women going there independently.

The increased role of Australian women in extremists groups is "deeply, deeply concerning", Ms Bishop said.

She said the government needed to work closely with communities and families, who are the "first line of defence".

"They'll be the ones that can detect changes in behaviour, or determine what their children are up to," she told Sky News.

"They are seemingly young Australians who think they are going off on an adventure - well they're not. They're joining terrorist organisations that are carrying out shockingly brutal attacks."