Calls have been made to unite against racism as activists claim it has 'seeped into British society' with the rise of the far right.
Stand Up to Racism welcomed a founding member of the Anti Nazi League to one of their Norwich meetings on Thursday evening.
And Paul Holborow, of the north London branch, said we are facing a 'very serious situation' in the wake of the Christchurch mosque shootings.
He said there is a 'pattern' between atrocities committed by those with far-right ideologies including the murder of Jo Cox and the killings by Anders Brievik.
'The shocking thing is the hard right are not lying low as you would expect,' said Mr Holborow.
'They are triumphant at what they achieved in New Zealand and this should really give us all pause for thought.
'We have a choice. We can say these are all very unfortunate and unpleasant acts, or we can say this is a pattern, and I have a horrid feeling the events in New Zealand are going to be emulated elsewhere.'
Stand Up to Racism will be holding a counter-demonstration to the 'Brexit Betrayal' march, including Tommy Robinson and the UK 'yellow vests' in London on Friday.
Mr Holborow said a new mass movement is needed like Anti Nazi League of the 1970s which opposed the National Front.
'The problem is the circumstances are rather different,' he added. 'We have a much more organised international right wing, and a much more organised right wing in Britain.
'If you understand the scale of the challenge you need to be encouraged by the scale of the opposition.
'Our side is in the majority. It is a question of mobilising that opposition.'
Roshan Bykes, from migrant support charity New Routes Integration, also addressed the meeting.
Mr Bykes said the group 'deliver programmes and activities to newly settled people' with the aim of helping them integrate into the local community and society.
It includes English lessons, mentoring programmes or games of football.
'We think by making these connections people can become integrated and the barriers between people and migrants break down,' he said.
'The long term goal is the people we are working with can find employment. When people have a job they feel they are part of society.
'Not only are we facing racism and Islamophobia, but hostile policies from the Home Office. They are isolated from society and it is really important to give them an opportunity.'
He added refugees they work with in Norwich have reported racism.
'All the Muslim women we work with have experienced verbal abuse, and lots of the men have faced racism and discrimination,' he said. 'Norwich is becoming a lot more diverse and attitudes are changing.'
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