The police are failing to investigate hundreds of cases of anti-Muslim hate messages on the internet, according to a government-funded monitoring group.
Tell Mama, which records anti-Muslim attacks, says it recorded 1,432 cases of abuse in the last 22 months.
But Tell Mama has told the BBC it has only had a response from the police regarding 70 cases.
The Association of Chief Police Officers said it was working to address the concerns expressed by Tell Mama.
After recording details of the abuse, Tell Mama (Measuring Anti-Muslim Attacks) reports directly to the Association of Chief Police Officers (Acpo) hate crime reporting system.
The group - which was set up two years ago - told the BBC 5 live Investigates programme that the police response has been poor and last month it wrote a letter to the Acpo president Sir Hugh Orde, complaining about the lack of action.
It cited two prolific social media users who promote their anti-Muslim beliefs daily.
Fiyaz Mughal is the founder of the interfaith Faith Matters organisation, which runs Tell Mama.
"It is worrying for us, given that the number of call-backs and subsequently the number of investigations that have moved forward have been extremely small in comparison to the volume of hate crimes we have sent in to police forces," he said.
"They go from harassment and abusive name-calling right the way through to threats - threats to come round to somebody's house and harm them, threats to attack or do something to a mosque, threats even to burn a mosque.
"That's the level of what we are passing through and there have been numerous occasions where we have sent information about direct threats to mosques, which frankly we haven't heard anything about. That is worrying."
Social media abuse
One 25-year-old woman victim told 5 live Investigates she was targeted by a man who posted a photograph of her on Twitter and called her an ugly Pakistani.
His followers commented on her appearance and there were racist overtones in many of the messages. He tweeted that "he lives very close to her" and a supporter of the English Defence League identified where it was.
But when she reported the matter to the police they said they could not do anything.
She told the BBC: "I made a statement and the police said it was quite difficult to do anything because it's quite difficult to prosecute someone when it comes to online abuse.
"They told me the evidence was no longer there, that it was difficult to identify who he was and there was just so much online abuse. The police said they'd be in touch but that was a week ago and I still haven't heard anything."
Anyone posting an offensive comment online can face charges under the Communications Act, or be charged with inciting racial or religious hatred.
The Crown Prosecution Service published guidelines in the summer on prosecutions involving social media and it set a high threshold for prosecution. Simply being offensive, shocking or disturbing is not enough.
But the CPS said any messages that amount to a credible threat of violence, a targeted campaign of harassment against an individual or which breach court orders should be "robustly prosecuted".
Acpo said reports of online hate messages were sent through to individual forces to investigate. Acpo has no role in monitoring how those forces handle those cases - that is a matter for each chief officer.
Supt Paul Giannasi, a member of Acpo's hate crime group, said: "The huge increase in the reporting of hate material on the internet has presented major new challenges for the police. We have met with Tell Mama and have discussed their concerns. In response, we have worked with forces to develop an audit process so senior officers can analyse how their forces are responding to these and similar reports. When it is circulated it will allow all areas to monitor their own performance.
"Acpo and the College of Policing have also developed new guidance to colleagues about how to respond to these issues. We have heard the concerns of Tell Mama and we are working with them to address their concerns and improve communications."
He said some forces had problems keeping on top of the sheer number of reports coming in and, because many social media companies were based in the US, there were also difficulties in securing evidence such as details of the IP address, which identifies the computer of the alleged perpetrator.
Acpo has its own website for reporting hate crime and the police urged anyone who thinks they are a victim of hate crime to report it.
You can listen to the full report on 5 live Investigates on Sunday, 24 November, at 11:00 BST on BBC 5 live.