Trump and Putin take centre stage at G20

Trump’s aides said prior to the event that he wants a “constructive dialogue” with Putin, but also that he has no specific agenda for the meeting.

"It's whatever the president wants to talk about,” general Herbert Raymond McMaster, his security adviser, said last week.

Trump in a speech in Warsaw on Thursday pledged allegiance to Nato and urged Russia to halt its “destabilising” activity in Ukraine.

He said on allegations that Russia meddled in the US elections to help him win: “I think it was Russia, but I think it was probably other people and/or countries.”

For his part, Putin wrote in Handelsblatt, a German newspaper, that he too wants a “working dialogue” but that the EU and US should lift economic sanctions on his country.

The US leader will also meet his Chinese counterpart, Xi Jinping, to discuss how to handle North Korea’s recent missile tests as well as tensions between US and Chinese navies in the South China Seas.

For her part, German chancellor Angela Merkel said on Thursday that she is prepared to talk long into the night to get a robust summit communique on climate, free trade, and migration.

"The negotiations are not easy,” she said.

The G20 statement is being seen by Germany as a counterpoint to Trump’s anti-Paris Agreement and protectionist policies.

China, the world’s biggest polluter, and India have already pledged to support Paris despite the US decision.

The EU on Thursday concluded a free trade pact with Japan to show that its trade agenda was alive and well.

But anti-globalisation protesters in Hamburg on the eve of the G20 came out in their thousands to make known their views on trade, with German police forced to make 76 arrests.

Merkel is also planning to hold separate talks with French leader Emmanuel Macron and Putin on Ukraine.

France and Germany brokered the so-called Minsk ceasefire agreement on the conflict, but neither Russia nor Ukraine have fulfilled Minsk provisions, with daily fire still reported on the contact line three years after fighting began.

Putin is also expected to meet with European Commission head Jean-Claude Juncker on Friday morning to discuss the Nord Stream 2 gas pipeline to Germany.

The Commission wants to negotiate the legal model for the project on behalf of the EU, with Nordic and eastern EU states up in arms over the idea of concentrating almost all Russian gas exports to Europe in German hands.