There has been a large increase in anti-Muslim incidents since the murder of Drummer Lee Rigby in Woolwich, an inter-faith organisation has said.
Faith Matters, which runs a helpline, said they had received 162 calls since Wednesday's attack, up from a daily average of six.
A number of people have been charged after allegedly offensive comments were made on social media websites.
Meanwhile, three more arrests have been made in connection with the murder.
Drummer Rigby was killed near Woolwich Barracks on Wednesday.
On Saturday night, two men, aged 24 and 28, were arrested by Met Police counter-terrorism detectives at a residential address in south-east London.
At roughly the same time, a 21-year-old man was arrested in the street in Charlton Lane, Charlton, south-east London.
Taser stun guns were used on both the 21-year-old and the 28-year-old but neither required hospital treatment.
The Met Police said officers were also carrying out search warrants at four further south-east London homes on Saturday night.
Shortly after the killing of Drummer Rigby, 28-year-old Michael Adebolajo was filmed by a passer-by saying he had carried out the attack because British soldiers killed Muslims every day.
Mr Adebolajo and a second suspect, Michael Adebowale, 22, were arrested at the scene and remain in a stable condition in hospital after they were shot by police. Both men were known to the security services, sources told the BBC.
A further 29-year-old man, arrested on Thursday on suspicion of conspiracy to murder, has been bailed to return pending further inquiries.
'Significant online activity'
Fiyaz Mughal, director of Faith Matters, said the nature of anti-Muslim incidents since Wednesday's murder, ranged from attacks against mosques, graffiti, the pulling off of Muslim women's headscarves and more general name calling and abuse.
He told BBC Radio 5 Live: "What's really concerning is the spread of these incidents. They're coming in from right across the country.
"Secondly, some of them are quite aggressive very focused, very aggressive attacks.
"And thirdly, there also seems to be significant online activity... suggesting co-ordination of incidents and attacks against institutions or places where Muslims congregate."
Since the attack, a number of people have been charged by police after allegedly offensive messages were posted on social media websites.
These include a 22-year-old man from Lincoln, a 28-year-old man from London, a 23-year-old woman from Southsea, and a 19-year-old man from Woking.
Three men - two from Gateshead and one from Stockton - have been arrested by Northumbria Police on suspicion of posting racist tweets.
It came ahead of a protest by the English Defence League (EDL) in Newcastle in which around 1,500 people took part. It had been planned for months.
A friend of Mr Adebolajo, Abu Nusaybah, was arrested on Friday night on BBC premises following an interview with BBC Newsnight.
The arrest was not directly related to the murder of Drummer Rigby, the Met Police said.
Mr Nusayabah told the programme that Mr Adebolajo had rejected an approach by MI5 to work for them around six months ago.
He said it followed a trip to Kenya where Mr Nusaybah said Mr Adebolajo had been detained by security forces.
He said he noticed "a change" in Mr Adebolajo when he returned from Africa last year.
Abu Nusaybah said Mr Adebolajo suggested he had been physically and sexually abused during an interrogation in a prison cell in the African country.
However, a spokesman for the Kenyan government, Muthui Kariuki, told the BBC Mr Adebolajo had never been to Kenya.
"I have been in touch with our security people, and I have been assured by all the relevant departments that... [he] has never been to this country."
Next week the director general of MI5 Andrew Parker is expected to present an initial report on the role of the security services to a Parliamentary committee, which is carrying out an investigation.
Media reports have suggested that both suspects attended the University of Greenwich.
But in a statement released on Saturday, vice-chancellor Prof David Maguire said the university had no records relating to Mr Adebowale.
"Our records show that a Michael Adebolajo was registered in academic years 2003/2004 and 2004/2005. His academic progress was unsatisfactory and he was not permitted to complete his studies here," he said.
Prof Maguire also said an investigation was being launched into whether there was any evidence of extremism, past or present, at the university.
Meanwhile, the father of Damilola Taylor, the schoolboy stabbed to death in Peckham in 2000, has told ITV News he acted as a mentor to Mr Adebowala.
He knew him since the age of 10 and became his mentor after his mother got in touch to say he was experiencing problems in school and was being bullied.
"He was a young, loving boy" but later it appeared there were issues around gangs and drugs, said Mr Taylor.
He said he last spoke to Mr Adebowla about two months ago and believes others had more influence over him.
Both Mr Adebolajo and Mr Adebowale, Britons of Nigerian descent, are understood to be converts to Islam, with Mr Adebolajo originally coming from a Christian family.
Maajid Nawaz, from the anti-extremism think tank the Quilliam Foundation, told BBC Radio 4's Today programme there is a "disproportionate number of convicted terrorists who've come from a conversion background".
Batool Al-Toma, an Irish-born woman who converted to Islam 25 years ago, said converts may be "vulnerable" to more radical views because they feel a "sense of isolation and alienation from family and friends".
Speaking about the fight against the rise of the extremist ideology, Chief Constable of Greater Manchester Police Sir Peter Fahy told the BBC there had been a "steady stream of plots", which had on the whole been foiled by police.
But he said the police and the security services were "particularly concerned" about people travelling from Britain to conflict areas such as Mali, Syria and Iraq and the increase in extremist websites.
Tributes have continued to be paid to Drummer Rigby, with a steady stream of well-wishers adding to the hundreds of flowers already placed near the scene of the killing.
Scores of motorcyclists supporting the Help For Heroes charity rode past the scene in a show of support for Drummer Rigby's family.
And a "solidarity march" by the Nigerian community took place on Saturday morning from Plumstead station to Woolwich town centre.
On Friday, Drummer Rigby's wife Rebecca, the mother of his two-year-old son, said she had been aware of the dangers of her husband serving in countries where there was armed conflict, including Afghanistan, but added: "You don't expect it to happen when he's in the UK. You think they're safe."
She said: "I love Lee and always will. I am proud to be his wife. He was a devoted father to our son Jack and we will both miss him terribly."
Drummer Rigby's stepfather, Ian Rigby, said: "We would like to say 'Goodnight Lee, rest in peace our fallen soldier. We love you loads and words cannot describe how loved and sadly missed you will be'."