One notice, signed by several residents, read: “Everyone is welcome here – except bigots.”
Another addressed “to our European friends” was also signed by residents.
Police are treating the original poster, which was headed “Happy Brexit Day”, as a “racially aggravated public order incident”.
Copies of the notice entitled were found stuck on fire doors across every floor of the 95-home tower on Friday, the day the UK left the EU after 47 years.
The messages read: “As we finally have our great country back we feel there is one rule that needs to be made clear to residents.
“We do not tolerate people speaking other languages than English in the flats. We are now our own country again and the the Queens [sic] English is the spoken tongue here.”
It said anyone who wanted to speak a different language should return to the country they “came from” and give back their flat to the council so “we can return to what was normality before you infected this once great island”.
A 67-year-old resident of the block, who did not want to be identified, told the Norwich Evening News: “When I saw the first poster I was absolutely disgusted. We live in a tower block and for that reason are already looked down upon – this has just made that worse.
“I love living here, and I am proud to live here – ordinarily it is a peaceful and lovely place. However, whoever this coward is, they have given everyone else here a bad name.”
Norwich City Council said it would not tolerate the behaviour of those who created the signs.
Nannette Youssef, a city councillor, wrote: “This despicable behaviour has no place in Norwich. We need to stand together, united in the face of racism ... God save our beautiful, diverse country.” She called on police and the city council to investigate fully.
Jake Humphrey, a television presenter, tweeted: “This trending photo from a door in Norwich makes me livid & embarrassed. Norwich is the most tolerant, accepting, loving city I have ever lived in or visited. This photo in no way represents our county or city. A racist, bigoted minority will NEVER be tolerated & NEVER prevail.”
The group Stand Up to Racism Norwich said of the backlash: “This is what we do: grassroots, community-led, collective action that gives everyone the confidence to challenge racism & fascism.”
After Sunday’s show of support, resident Rosemary Miller told the BBC: “We all stood round the tower holding hands and saying that we were a multicultural building and everybody is welcome.
“I put on the wall [a sign saying] ‘let’s live in a city of love for all, we love our tower block, we love everybody, we are all family’.”
Norfolk Police said no arrests had been made and its investigation was continuing.
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