Donald Trump and Vladimir Putin had a "robust and lengthy" exchange over Russian interference in the US elections and agreed to a new ceasefire agreement for Syria in their first fact-to-face meeting.

The two leaders met on the sidelines of the G20 summit in Hamburg for talks in which they also discussed the war in Ukraine, the North Korean nuclear crisis and cyber security.

But the highly-anticipated meeting began with what Rex Tillerson, the US secretary of state, described as a “very robust and lengthy exchange" about Russian interference last year's presidential election, in which Mr Putin demanded proof of alleged Russian involvement.