German and French authorities have begun work on a three-pronged strategy behind the scenes amid escalating fears that the eurozone’s sovereign debt crisis is spiralling out of control.

Their aim is to build a “firebreak” around Greece, Portugal and Ireland to prevent the crisis spreading to Italy and Spain, countries considered “too big to bail”.

According to sources, progress has been made at the G20 meeting in Washington, where global leaders piled pressure on the eurozone to fix its problems before plunging the world back into recession. In a G20 communique issued on Friday, the world’s leading economies set themselves a six-week deadline to resolve the crisis – to unveil a solution by the G20 summit in Cannes on November 4.

Sources said the plan would have to be released as a whole, as the elements would not work in isolation.