David Miliband defies Ed to insist intervention in Syria is 'increasingly necessary' Former foreign secretary says aid workers under attack in Syria Calls for an end to the 'diplomatic and military deadlock' for action More than 6m Syrians forced out of homes with 2m leaving the country President Obama confident Congress will back his planned attacks Michael Gove condemns Labour 'celebrating' vote against military strikes David Miliband today put himself at odds with his Labour leader brother Ed to warn that international intervention in Syria is "increasingly necessary." The former foreign secretary condemned the failure of western governments including Britain to "break the diplomatic and military deadlock" and warned humanitarian aid cannot reach refugees because aid agencies are coming under "aerial bombardment." His warning that Syria risks becoming a "dangerous no-man's-land" like Afghanistan appears at odds with Ed Miliband's insistence that Labour will not back a second vote on UK military intervention. Action: David Miliband (right) warned that the unpopularity of international action in Syria must not be an excuse for inaction, despite his brother Ed (left) ruling out British intervention There have been growing signs of division in Labour ranks since David Cameron's call for action was rejected by a majority of 13 MPs in the Commons last week. But last night a senior Labour source warned: "We caution against any idea of a rerun of a Syria vote. It is thought that some on the Labour frontbench were spooked by polls showing the public was overwhelmingly against another British military foray in the Middle East. David Miliband, who lost out on the Labour leadership to his brother three years ago, quit the Commons to become chief executive of New York-based aid charity International Rescue Committee. In an article for the Financial Times, he argued that the unpopularity of international action in Syria was not an excuse for inaction. He said: "It is clear that, while international engagement is decreasingly popular in the advanced democracies, a multipolar world makes it increasingly necessary. Humanitarian intervention is about human need, not political sides - but it has political consequences. There is capacity to save more lives, but this needs resources and political will. The drums of war are reason to redouble humanitarian efforts, not forget them. It comes after it emerged the Syrian civil war has now forced 2million refugees to flee the country. He insisted that "none of the military options being canvassed - or, in the UK, rejected - promises a decisive shift in the course of the conflict." An audit by the IRC reveals a grim "litany of suffering," adding: "The dynamics are all going in the wrong direction and the prospects are bleak. For geopolitical reasons, as well as basic humanity, we need a fundamental step change in the scale of effort. US President Barack Obama today said he was confident that Congress would back his plan for intervention in Syria. French president Francoise Hollande said he would to wait for the US Congress decision on military action in Syria before deciding on any action France might take. Meanwhile Michael Gove today accused Labour MPs of behaving like fans at a "football match" cheering at the result of the Commons vote against military action in Syria.