Islamic State has "global ambitions", and representatives of governments and technology giants said in Australia on Thursday that more must be done to tackle the group's use of social media for recruitment.

Australian Prime Minister Tony Abbott told the regional extremism conference it was vital to find ways to stymie the ideology of extremists who are drawing thousands of foreign fighters to Iraq and Syria.

"You can't negotiate with an entity like this. You can only fight it," he said of Islamic State, speaking to an audience that included high-level officials from 30 nations, as well as users of Facebook, Twitter and Google.