The public make more than 3,600 contributions to the fight against terror every day, Britain's most senior counter-terrorism police officer says.

Assistant Commissioner Mark Rowley said co-operation between police and the public was the "greatest advantage".

He cited anti-terrorist hotline calls and the reporting of suspicious online content as ways to keep the UK safe.

But he said with the terror threat ranked as "severe" since 2014, "even more public assistance" was needed.

The threat to the UK is at the second highest of five possible levels, meaning an attack is highly likely.

Mr Rowley said some were passing information to authorities about people behaving unusually in public places, while others were raising concerns about neighbours and friends becoming "more extreme".

He told BBC Radio 4's Today programme it was "really important" for authorities to be able to intervene before people's beliefs become too extreme - saying about 60 to 70 cases a month were being resolved.

About one sixth of those came from public referrals, he added.

'Not complacent'

Asked if some of the referrals were stopping people being murdered or falling victim to acts of terrorism, he replied: "Yes."

He added: "We are drawing people back from a path towards extremism through partnership activity. Even if you take a view that 90% of those people may have self-treated or not gone on to become terrorists, that is still a massive effect."

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In a blog post for the National Police Chiefs Council (NPCC), Mr Rowley said: "Every call, every referral, every briefing is part of our joint fight against terrorism.

"The information we receive helps our investigations, intelligence-gathering and preventative work; they help us carry out significant protective security operations; they help us get the right support for vulnerable people, and they undermine the plans of terrorists."

Other examples of the "collective effort" referred to by Mr Rowley include people visiting police and government websites for advice on how to protect homes and businesses or stay safe in the event of an attack.

Dr Alan Mendoza, the founder of the Henry Jackson Society - a think tank which aims to combat extremism - said the longstanding public participation in combating terror crimes had been a "tremendous boon to the British notion of social cohesion".

He cited the example of Isa Ibrahim who was arrested after members of the Muslim community contacted the police with concerns. Ibrahim was jailed in 2009 for making explosives with intent and preparing terrorist acts.

"We are all in this together on the basis of the fight against terrorism," Dr Mendoza added.

On Sunday, Metropolitan Police Commissioner Sir Bernard Hogan-Howe warned a terror attack in Britain is a case of "when, not if".

In his blog, Mr Rowley - a Met assistant commissioner and the NPCC lead for counter-terrorism policing - said officers were not complacent and he "couldn't agree more" with Sir Bernard's assessment.

He said the UK's tight gun laws and a close working relationship between police and the security services were an advantage.

Mr Rowley said: "But for me our greatest advantage is the co-operation between the public and the police.

"It has often been said that 'communities defeat terrorism' and now that's more important than ever before."