Boris Johnson has failed to secure the backing of the G7 nations for swift sanctions against Russia and Syria, leaving the US-UK plan to pressurise Vladimir Putin in tatters.

Germany and Italy vetoed the idea of targeting Russian and Syrian military leaders until an investigation has been carried out into who was to blame for last week’s nerve gas attack in Idlib province.

The Italian Foreign Minister Angelino Alfano said Mr Putin “must not be pushed into a corner”, suggesting Italy may not support extra sanctions even if an investigation proves Assad was to blame.