A statement from the force urged people not to gather in groups of more than six as per public health advice to prevent the spread of coronavirus. It said those who did wish to protest in the capital would have to obey a 5pm curfew, warning ‘violence will not be tolerated’.

It comes as Boris Johnson faces mounting pressure to show ‘national leadership’ by tackling racism in the wake of the Black Lives Matter demonstrations.

Black Lives Matter (BLM) had already cancelled a planned rally in Hyde Park at 1pm on Saturday, warning that ‘many hate groups’ were threatening the safety of those coming.

‘We want the protests to be a safe space for people to attend’ a post from the BLM LDN organisers said. ‘However, we don’t think it will be possible with people like them present.’

Far-right groups, with the support of extremists such as Stephen Yaxley-Lennon, who calls himself Tommy Robinson, plan to hold a ‘defend our memorials’ event at Winston Churchill’s statue on Parliament Square in the afternoon.

The monument to the wartime prime minister was daubed in graffiti describing him as a racist on Sunday, and has since been bordered up to prevent further vandalism.

Local authorities across the country have vowed to review statues and memorials with links to the slave trade and the British Empire after the toppling of Edward Colston last weekend. After several others came down in London, a network of football hooligans and extremists said they would rally to ‘defend’ national monuments.

There are fears among anti-racist campaigners that these groups will seek out BLM protesters with the intention of confronting them.

Sadiq Khan has urged Londoners to stay at home, saying the potential for disorder over the next few days is ‘very real’, with the far-right ‘organising counter-protests in London in the hope of provoking violence and discrediting a legitimate cause’.

It is unclear if anti-racism protesters will heed calls to stay away as many protests are still scheduled to take place, the Met Police say.

Today, thousands gathered peacefully in central London, St Albans and other locations across the country to protest against racism and police brutality. It comes after the death of George Floyd at the hands of US police in Minneapolis, which has sparked the biggest global uprising against racism since the 1960s.

In the UK, the vast majority of protests have been peaceful, though the Met criticised a minority for instigating violence at demonstrations last weekend in their statement this evening.

Commander Bas Javid said: ‘I absolutely understand why people want to make their voices heard – there is a really strong depth of feeling out in the communities, but the government direction is that we remain in a health pandemic and people are asked not to gather in large groups.

‘By doing so, you are putting your own safety, and that of your family or friends at risk. We are asking you not to come to London, and let your voices be heard in other ways.’

He added: ‘We all saw the crowds that came together last weekend, and the demonstration on the whole was peaceful and reinforced the legitimacy of feelings within our communities.

‘However on both days, there was a minority intent on disorder, which resulted in incidents of violence and criminal behaviour, and assaults against our officers. This cannot be tolerated.

‘As part of the ongoing policing operation ahead of tomorrow’s demonstrations, we continually monitor information available to us. Based on current information, and in order to keep those people safe who plan to come and protest, we have made the decision to impose conditions on the planned demonstrations tomorrow.’

As well as the 5pm curfew, police have imposed restrictions on the routes that can be taken by each group of protesters.

However, their position is that those who were planning to come to London should reconsider. Police say the decision to impose conditions does not mean the protests are authorised.

This comes as Boris Johnson faces criticism over his response to the Black Lives Matter protests.

The PM said on Friday it was ‘shameful’ that the statue of Winston Churchill, who helped lead Britain to victory against Hitler in the Second World War, was at ‘risk of attack by violent protesters’.

A debate rages on across Britain over whether or not to tear down monuments of people who held racist views or played a part in slavery. Mr Johnson said taking statues down would be to ‘lie about our history’ and said protesters should ‘look at the positive stuff’.

He said the country had ‘made huge progress in tackling racism’ and would continue to do so, though he didn’t set out plans for what steps he would take to improve the lives of black people in Britian.

After saying he understood ‘why people feel outraged’ at what happened to George Floyd in the US, he urged people to stay away from protests scheduled for the weekend, predicting they would ‘end in deliberate and calculated violence’.

Shadow home secretary Nick Thomas-Symonds said Boris Johnson needed to recognise the ‘deep hurt’ felt by black people in the UK and set out steps for ‘meaningful action’.

‘It is clear that the weekend ahead is likely to cause major challenges, with the risk of violence in our streets, not least as far-right extremists seek to exploit the situation and sow hate for their own divisive ends’ he said.

‘I have no doubt that police across the country have the skills, experience and dedication to respond as well as possible to the challenge, and the vast majority of protesters intend to be peaceful.

‘However, the Prime Minister should be showing national leadership, by co-ordinating the government’s response to the complex issues underpinning these protests.

‘This means recognising the deep hurt so many black people in our country have spoken so powerfully about, and setting out steps for meaningful action against racism in our country

‘This is a powerful moment in our history and it is important the Prime Minister is not found to be wanting.’

Mr Floyd died after a white police officer held him down by pressing his knee into his neck for almost nine minutes in Minneapolis on May 25.

Today, BLM campaigners unveiled a billboard on Westminster Bridge Road in central London, near to Parliament, highlighting the plight of black people in the UK.

Forming the words ‘I can’t breathe’ – uttered by Mr Floyd as he choked – the poster lists more than 3,000 names of people who have died in police custody, prisons, immigration detention centres and in racist attacks in the UK, as well as those who have died with coronavirus and in the Grenfell Tower fire.