Protesters have clashed with police outside a pro-Donald Trump black tie event in Washington DC, as tens of thousands of people prepare to take to the streets to oppose his presidency.

Demonstrators had gathered outside the National Press Club on Thursday night to oppose a group of Trump supporters who were staging a "DeploraBall", an event named after Hillary Clinton branded them a "basket of deplorables" during the election.

Footage posted on social media appeared to show police in riot gear using pepper spray and tear gas to disperse the protesters.

One Trump supporter claimed to have been attacked by a protestor wielding a flagpole. James Allsup, 21, told Fox News: “I was wearing my ‘Make America Great Again’ hat, and a white male came up behind me and swung at me with a flagpole - I kind of blacked out for a minute,' “Before I knew it my head was gushing blood - there’s blood on my Trump hat.”

Mr Allsup posted on his facebook page: “Remember this is what happens when you disagree with the ‘tolerant left’.”

Protesters, however, denied they had been violent.

A woman walks past protestors outside the National Press Club, the venue for the Deploraball (Paul J. Richards/AFP/Getty)

A Washington Metropolitan Police spokesman said the situation was "dynamic" and could not confirm whether any arrests were made.

Protesters were seen booing whenever ball-goers in suits, tuxedos or dresses came in or out of the event.

Witnesses said one man waving a pro-Trump flag had debris thrown at him and was chased to the nearby Warner Theatre.

The clashes came as tens of thousands of people prepare to stage protests in cities around the world on Friday when Mr Trump will be sworn in as US president.

Security officials have expressed concerns about possible clashes between supporters and opponents of Mr Trump in Washington, where up to 900,000 people are expected to watch him take the oath.

Coalition protest group DisruptJ20 has vowed to disrupt Mr Trump's inauguration and interfere with security checkpoints.

Activists protest Donald Trump's proposed Muslim ban Show all 11 1 /11 Activists protest Donald Trump's proposed Muslim ban Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty Activists protest Donald Trump's proposed Muslim ban People listen to speakers at a demonstration against racism and conservative presidential candidate Donald Trump's recent remarks concerning Muslims on December 10, 2015 in New York City. Dozens or demonstrators and activists converged at Columbus Circle to denounce the politics of Trump and the treatment of Muslim refugees both in America and Europe. Spencer Platt/Getty

In contrast, Bikers For Trump will rally on Washington's Pennsylvania Avenue to celebrate Mr Trump's inauguration.

Outgoing homeland security secretary Jeh Johnson said 28,000 officials will be involved in the security operation in Washington, including more than 3,000 police officers and 5,000 members of the National Guard.

He told MSNBC: "The concern is some of these groups are pro-Trump, some of them are con-Trump, and they may not play well together in the same space."

Film-maker Michael Moore will speak at a rally in Washington's McPherson Square on Friday afternoon, where some 20,000 people are expected to attend.

On Thursday, Moore was joined by Hollywood stars Robert De Niro, Julienne Moore and Alec Baldwin during a large protest outside Trump International Hotel in New York.

Anti-war group, the Answer Coalition, is planning demonstrations at the US Navy Memorial and Freedom Plaza near the White House.

Meanwhile, a group calling itself Occupy Inauguration plans to rally on the morning of the inauguration ceremony at Meridian Hill Park, about a mile and a half north of the White House.

The group said speakers at the rally will include 2016 Green Party presidential candidate Jill Stein.

In the UK, protests against Mr Trump have already begun.

The largest anti-Trump demonstration in America is expected to take place in Washington on Saturday when some 200,000 people are expected to join a women's march.

Celebrities including Scarlett Johansson, Amy Schumer and Patricia Arquette have pledged they will attend the protest, while similar events are being planned in a number of US cities including Los Angeles and Park City, Utah.

Ugly Betty star America Ferrera, who is helping organise the Washington protest, said: "Since the election, so many fear that their voices will go unheard.

"As artists, women, and most importantly dedicated Americans, it is critical that we stand together in solidarity for the protection, dignity and rights of our communities."