Demonstrators have vowed lay siege to Downing Street in a bid to hamper Donald Trump’s state visit to Britain, despite police imposing a ban on marching down Whitehall.

Tens of thousands of protestors are set to descend on central London on Tuesday to voice their opposition to the US President as he meets outgoing Prime Minister Theresa May.

The Metropolitan Police said it would prevent the demonstrators marching past Downing Street from Trafalgar Square and into Parliament Square.

That raises the prospect of clashes at the barriers being erected by police just north of the Women’s War Memorial to stop marchers gathering outside the gates to No 10.

Activists have pledged to hold a ‘Carnival of Resistance’ to disrupt the president’s visit.

Lindsey German, of the Stop the War Coalition, one of the groups backing the protest, said: “We are determined to get as close to Downing Street as possible. The Prime Minister has just resigned and invited over a racist, sexist warmonger. If the Tories think that’s a good idea then they better think again.”

Senior officers want to avoid the prospect of climate change activists and other militants staging blockades and sit-down protests outside the gates of Downing St, in a repeat of the scenes which brought chaos to parts of central London last month. Police were criticised for not clamping down on the Extinction Rebellion protests and are keen not to be caught out again.