Fiyaz Mughal, founder of Tell MAMA, an organisation which documents hate crimes against Muslims in the UK, said the increase in hate crimes and attacks on mosques were part of a rising tide of online hate which has spilled out on to the streets.

He said: "Political events have supercharged the sense of confidence in sections of our population which probably held those (extremist) views and didn't voice them before, but felt confident in voicing them over the last few years."

"What's happening in terms of the targeting of mosques also corresponds with what is taking place on a street level against visible Muslims," he added. "What is happening in mosques is basically a reflection of wider society."

His comments echo those of Labour's shadow home secretary Diane Abbott, who said: "Politicians have a particular responsibility in the language they use, the policies they advocate and the climate they create.

"There should be a unanimous message that violence against any section of our society is unacceptable."

When Mr Mughal founded Tell MAMA in 2012, "over 60% of cases" reported to the organisation occurred online, he said.

As some social networks have introduced more measures allowing users to report hate speech online, the number of examples of online hate speech reported to Tell MAMA have decreased while real-world hate crimes have risen sharply.

"If you look at the picture now," he said, "over 75% of our cases are street-based", compounding some Muslims' previous experiences of online abuse and driving a wedge between communities.

"The targeting of a mosque is a message of hate that targets the whole local population that uses that institution," said Mr Mughal. "And that has huge ramifications not just on cohesion or personal safety but on extremism as well."

The Home Office has announced a new national hub to tackle what it called the "emerging threat" of hate crime online.

Mr Mughal recommended a multi-pronged strategy to deal with the increase in hate crime, including "consistent" sentencing of perpetrators, more education around hate crime "to support schools", and better policing of online spaces where extremist views fester.

"I know of cases when mosques have been attacked and individuals who have gone out of their way to threaten worshippers have got suspended sentences and walked out of court," he said.

"The message that sends out to those communities is basically that your voice is not being heard or that your mosque is not that valuable. And it further compounds the problem."

By Alastair Reid