Barack Obama to welcome Donald Trump to White House

US President Barack Obama is set to meet his successor Donald Trump in the Oval Office for talks aimed at ensuring a smooth transition of power.

However, thousands of demonstrators took to the streets in several cities to voice their opposition to Mr Trump.

They shouted the slogan "Not my President", a term that was also trending on social media.

Mr Trump will become the 45th US president after securing a surprise victory over Hillary Clinton.

Mr Obama - who had branded Mr Trump "unfit" for office and campaigned against him - urged all Americans to accept the result of Tuesday's election.

"We are now all rooting for his success in uniting and leading the country," he said.

Defeated Mrs Clinton also told supporters Mr Trump had to be given a "chance to lead".

Despite their calls, protesters gathered in several cities across the country.

In New York, thousands marched on Trump Tower, voicing their opposition to Mr Trump's policies on immigration, gay rights and reproductive rights.

Police earlier erected concrete barriers and other security measures outside the 5th Avenue skyscraper, which is likely to be Mr Trump's headquarters during the transition to power.

In Chicago crowds reportedly blocked the entrance to Trump Tower, chanting: "No Trump, No KKK, No Fascists USA" and "Not my president!"

American flags were burnt at some protests and in Portland, Oregon, demonstrators temporarily closed an interstate highway. Demonstrations also took place in Philadelphia and San Francisco.

In his victory speech in the early hours of Wednesday, Mr Trump vowed to "bind the wounds of division", after the acrimonious election contest, and to be "president for all Americans".

White House spokesman Josh Earnest has insisted Mr Obama will be sincere about ensuring a smooth handover when he meets Mr Trump, although he added: "I'm not saying it's going to be an easy meeting."

The president-elect will be accompanied to the White House on Thursday morning by his wife, Melania, who will have a meeting with First Lady Michelle Obama in the White House residence.