NEW laws on freedom of speech could result in a backlash from "alienated" Muslims, the UK Government’s independent reviewer of counter-terrorism legislation has warned.

David Anderson QC said the components of the forthcoming Counter-Extremism Bill would place limits on "some of our most basic freedoms", which could trigger a negative reaction from terror groups.

His warning came as Andrew Parker, the head of MI5, said terrorist plotting against Britain was at its most intense for three decades and was still growing as he backed new powers to monitor communications.

In his fifth annual review today, Mr Anderson said: "If the wrong decisions are taken, the new law risks provoking a backlash in affected communities, hardening perceptions of an illiberal or Islamophobic approach, alienating those whose integration into British society is already fragile and playing into the hands of those who, by peddling a grievance agenda, seek to drive people further towards extremism and terrorism."

Full details of the Counter-Extremism Bill have not been made public but they are expected to include tough new clampdowns on extremist organisations who use hate speech in public places, and new powers for Ofcom to take action against outlets which broadcast extremist content.

Mr Anderson said UK-based extremists were able to talk directly to Isis fighters and their wives in web forums and on social media.

"The key risk is that this propaganda is able to inspire individuals to undertake attacks without ever travelling to Syria or Iraq. Through these media outputs, (terrorists have) inspired the increase in unsophisticated but potentially deadly attack methodologies."

A Downing Street spokesman said he had not seen the report but noted: "The key point about the counter-terrorism strategy that the PM has set out is the need to really tackle the threat of radicalisation and prevent individuals being drawn into terrorism, wherever that happens.”

A Home Office spokesman welcomed Mr Anderson’s report and said: "The current threat from terrorism presents one of the greatest challenges to the UK's peace and security and protecting the public is our primary duty. We remain committed to ensuring that our counter-terrorism laws are fair, effective and proportionate in the face of this threat.”