Police in Switzerland have launched a criminal investigation into death threats made against US President Donald Trump who is due to visit the country.

According to The Local, one protester was seen at a march in the Swiss capital of Bern last week carrying a sign calling for Trump to be killed.

Hundreds took to the streets of the capital protesting Trump's pending arrival at the World Economic Forum (WEF) meeting in Davos.

One banner had an image of Trump, with a nuclear button and the slogan: "Kill Trump with his own weapons."

Police, after discovering the sign, have now launched an investigation into the possible incitement to commit a crime.

If charged, the person who held the banner could face up to three years in prison.

A similar probe is already underway based on a death banner aimed at the Turkish President Recep Tayyip Erdogan.

Protests are expected to continue ahead of next week's economic summit where business leaders and finance ministers are expected to gather to discuss the global economy.

Trump will be making his maiden appearance at the event as US president and is scheduled to meet French president Emmanuel Macron.

Officials in the UK had tried to organise a meeting between Theresa May and Trump at the summit, but those plans have reportedly collapsed.