The departure of President Bashar al-Assad is crucial to resolving the conflict in Syria, British Foreign Secretary Boris Johnson said ahead of talks with his US and European counterparts on Tuesday.
Johnson was scheduled to meet US Secretary of State John Kerry in London before talks on Syria with Kerry and the foreign ministers of Germany, France and Italy.
He and Kerry also planned to discuss Yemen over dinner with the foreign ministers of Saudi Arabia and the United Arab Emirates.
"We must be more active, more engaged and more outward-looking, so I am delighted to have this early opportunity to welcome my international counterparts to London for important meetings on the conflicts in Syria and Yemen," Johnson said ahead of the talks.
"I will be making clear my view that the suffering of the Syrian people will not end while Assad remains in power," he said. "The international community, including Russia, must be united on this."
Writing in a recent column in The Telegraph, before his appointment as foreign secretary last week, Johnson had argued that Western powers should cooperate with al-Assad and Russian President Vladimir Putin to find a solution to the Syrian conflict and subdue Islamic State forces.