Boris Johnson has made a fresh appeal for international action against Bashar al-Assad after a chemical weapons watchdog ruled an attack in Syria that killed more than 80 people used sarin nerve gas.

The Foreign Secretary said the Syrian president's brutal regime was behind the atrocity and insisted the findings of the probe "cannot be ignored".

In the wake of the massacre, Russia blocked a British-backed bid at the UN Security Council to condemn the attack and Mr Johnson failed to secure agreement on targeted sanctions at a meeting with G7 counterparts.

Mr Johnson urged international leaders to now "unite behind the need to hold those responsible for this atrocity to account".