David Cameron: UK jihadists to be made stateless if they join Isil Those who attempt to return in secret will face a five-year jail term under a new criminal offence. Mr Cameron was due to address Australian MPs in Canberra early this morning, British time, ahead of the G20 meeting of world leaders this weekend. "We have to deal with the threat of foreign fighters planning attacks against our people," he was due to say. But as well as dealing with the consequences of this threat, we also have to address its root cause. And let's be frank: it's not poverty, though of course our nations are united in tackling deprivation wherever it exists. It's not exclusion from the mainstream. Of course we have more to do but we are both successful multicultural democracies where opportunities abound. No, the root cause of the challenge we face is the extremist narrative. So we must confront this extremism in all its forms. We must ban extremist preachers from our countries. We must root out extremism from our schools, universities and prisons. The orders, to be signed off by the Home Secretary, would be made on the basis of "reasonable suspicion of involvement in terrorist activity." It is thought that officers could travel abroad to interview suspected jihadists and determine whether they are to be barred. When Mr Cameron first raised the prospect in August, Dominic Grieve, the former attorney general, said it was likely to be a "non starter" as making a person stateless is banned by the UN. The new powers attempt to address the issue by providing for return under tough conditions. They would also enable police and border officials at airports to seize the passports of suspected terrorists, including those aged under 18 on the spot. Currently the Home Secretary must approve such seizures individually under Royal prerogative, an unwieldy process. Security services have raised concerns at a growing number of jihadist teenagers. Salma and Zahra Halane, academically high-flying 16-year-old twins from Manchester, travelled to Syria this year and are thought to have married Isil fighters. Jaffar Deghayes, a 17-year-old British Muslim from Brighton, is thought to have died fighting in Syria. Airlines will be banned from flying terror suspects back to Britain and compelled to carry out additional passenger screening if requested. They will also be required by law to share passenger data. Those that fail to do so will face civil penalties, which could include banning them from landing in Britain.