US President Barack Obama has urged Donald Trump to "stand up" to Russia when it deviates from US "values and international norms".

Mr Obama was in Berlin on his last official tour of Europe when he was asked how his successor might handle Russia.

With German Chancellor Angela Merkel standing beside him, he said that Russia "has influence in the region and it has influence around the world and, in order to solve the problems around the world, it is in our interests to work with Russia and obtain their cooperation".

He added: "I've sought a constructive relationship with Russia but have also been realistic in realising that there are some significant differences between how Russia rules the world and how we view the world...In issues like Ukraine, Syria, we've had very significant differences.

"And my hope is that the president-elect coming in takes a similarly constructive approach, finding areas where we can cooperate with Russia, where our values and interests align but that the President-elect also is willing to stand up to Russia where they are deviating from our values and international norms."

Mr Obama said that Mr Trump, who expressed admiration for Russia's president Vladimir Putin during his campaign, did not have to follow "our blueprint or our approach" but he hoped Mr Trump would not just walk away from the progress made so far.

He said he had told Mr Trump that "what may work in an election campaign may be different to what works to unite a country", adding: "He has indicated he understands that."

Mrs Merkel said that she was approaching the Trump presidency with "an open mind" and that she was encouraged that the presidential process in the US was "working smoothly" so far.

The press conference comes as Europeans wait to see how their situation might change once Mr Trump takes office in January, following a campaign in which he said European countries should take more responsibility for their own defence and that he would quit some free trade agreements.