The public have been hailed by police for their help fighting terrorism but it’s still "when, not if" an attack will happen in London.

Assistant Commissioner Mark Rowley, the country's most senior counter-terror officer, has said the public make more than 3,600 "contributions" to the battle against terrorism every day.

The co-operation between the police and the public is the UK's "greatest advantage".

In a blog post for the National Police Chiefs Council, Mr Rowley added the UK's other counter-terrorism advantages include tight gun laws and a close working relationship between police and the security services.

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

"The true scale of that collaboration is impressive, but rarely explained. The fact is that we see at least 3,639 contributions from the public every day, helping keep us all safe in our collective effort against terrorism."

Members of the public assisted police by calling the confidential anti-terrorist hotline on average 32 times a day and making on average five referrals of extremist material online and two of potential radicalisation.

Mr Rowley added that, every day, some 300 people visit the Prevent Tragedies website, 1,750 National Counter Terrorism Security Office sessions - where specialist officers advise how to protect homes and businesses - are recorded and 1,550 people either take part in anti-terror briefings or watch a Stay Safe film.

"Every call, every referral, every briefing is part of our joint fight against terrorism," he said.

"All of these contributions are critically important to our ability to keep each other safe."

It comes after Met Police Commissioner Sir Bernard Hogan-Howe warned a terror attack in Britain is a case of "when, not if".

Writing in The Mail On Sunday he said: "I feel and understand that fear, and as the police officer in charge of preventing such an attack I know you want me to reassure you.

"I am afraid I cannot do that entirely. Our threat level has been at severe for two years. It remains there.

"It means an attack is highly likely - you could say it is a case of when, not if."

Explaining the work of the police, he pointed to the number of terror plots that had been foiled since the murder of Lee Rigby in May 2013, including one to murder officers at Shepherd's Bush police station, west London, and another to carry out a Lee Rigby-style attack on US soldiers in East Anglia.

The UK's top officer also said that the "British way of life and culture" made the UK hostile to terrorists.