Assad heaped scorn on British politicians for allowing the vote on leaving the EU, saying lawmakers who had criticised his handling of the civil war had shown themselves to be "disconnected from reality".
"Everyone is saying 'We need more reforms'. Nobody is saying what kind of reforms we would need in addition to those which are under way, including some initiatives we have taken in the field of the social dimension of the internal market," Juncker said.
US stocks extended their gains and were up for the fourth straight day as strong manufacturing data boosted prospects for an improvement in the economy.
Former London mayor Boris Johnson abruptly pulled out of the race to become Britain's next prime minister, in a shock move that upturned a political order shaken by last week's vote to leave the European Union.