Security services have thwarted 13 potential terrorist attacks on the UK in less than four years and run 500 investigations at any one time, Britain’s most senior counter-terrorism officer revealed.

Mark Rowley, assistant commissioner at the Metropolitan Police, revealed the statistics as a campaign urging the public to help identify terror plots across the country was launched today (March 6).

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The Action Counters Terrorism (ACT) appeal urges the public to report suspicious behaviour to the police. Mr Rowley said residents have assisted officers in a third of their most ‘high-risk’ investigations.

The senior officer stressed that the threat continues to be severe while authorities have some big operational challenges.

Investigators have been making arrests at a rate of close to one a day on average since 2014.

Mr Rowley said: "Some of that information acted on is a change in someone's behaviour, some of that's about suspicious activity.

"Sometimes that public information has actually started an investigation. Other times it's part way through and it corroborates some things or adds to things we already know.

"The public are making a great contribution, which is critical to us all working together to protect ourselves from terrorism."

Commander Simon Bray lead for the Met Police security and specialist operations, said "Last year a record number of people contacted the confidential Anti-Terrorist Hotline, with the service receiving more than 22,000 calls. Officers hope this number will continue to increase if more can be done to encourage people to call or report online.

In London we have excellent relations with our communities. These are the people that we depend on for information to help us keep Londoners safe. The number or calls and online reports we receive with information is increasing but we are appealing for even more."

Research to support the ACT campaign looked at public attitudes towards counter terrorism policing. More than 80 per cent of respondents said that it was important for communities to work with police to prevent terrorism.

A quarter of those surveyed said, however, they might not report their suspicions because of fears over wasting police time and 39 per cent were unsure about what suspicious behaviour might look like.

Commander Bray added: "Research has shown some people worry they might be wasting our time or they are not sure what sort of activity might be suspicious. So we want to allay those concerns and help them to help us make nothing happen by acting on their instincts."