Melania Trump 'trapped in hotel' as protesters surround building

The First Lady was due to be involved in an event for the spouses of leaders taking part in the G20 summit, organised by Angela Merkel's husband.

But a spokesperson for the US delegation told German media that they had been unable to get clearance for Ms Trump to leave the hotel where she is staying.

Trump has expressed her sympathies for those hurt in the protests which erupted across Germany's second largest city and urged people to remain safe on Twitter.

President Trump made it to the summit on time after driving through the city at a fast speed under heavy police escort. The German Chancellor's husband, Joachim Sauer, was due to take Trump on a tour of the German Climate Computing Centre with the US President's daughter, Ivanka Trump, and other spouses of G20 leaders on Friday.

German officials said the idea for the visit came from Sauer who is a professor of physical and theoretical chemistry. The centre, which uses super-computers to map climate change's effect on regions across the world, is situated near the secured hall where Merkel, President Trump, and other leaders are meeting.

Malcolm Turnbull, the Australian prime minister, tweeted that he was under "security lockdown" with the Indonesian president, Joko Widodo. Police protecting the hotel where Turnbull is staying briefly came face to face with protestors at one point.