ABOARD PAPAL PLANE - Pope Francis said on Tuesday that while it was ‘almost impossible’ to have a dialogue with Islamic State insurgents, the door should not be shut.

‘I never say 'all is lost', never. Maybe there can't be a dialogue but you can never shut a door,’ he told reporters on his plane returning from Strasbourg, France, where he addressed the European Parliament and the Council of Europe.

‘It is difficult, one could say almost impossible, but the door is always open,’ he said in response to a question about whether it would be possible to communicate with the militants. Ultra-radical Islamic State has captured thousands of square miles (km) of territory in Iraq and Syria, beheaded or crucified prisoners, massacred non-Sunni Muslim civilians in its path and displaced tens of thousands of people. The Iraqi govt has been trying to push back IS although  militias and Kurdish peshmerga have helped contain the Sunni insurgents and repelled them in some provinces. Pope Francis repeated comments made earlier this year that while it was legitimate to fight an ‘unjust aggressor’, this had to be supported by an international consensus.