The UK's second most senior counter-terrorism chief has highlighted the importance of officer numbers in the fight against extremism.

Assistant Chief Constable Terri Nicholson, deputy national coordinator for CT policing, said she considers all officers and staff crucial to her role.

"So many of our cases have origins in community intelligence. Trust and confidence is absolutely essential in that equation. Communities have got to trust us and they have to be assured we are going to deal effectively with things when they do step forward."

The officer said many people have made "really difficult decisions" to report that their relatives have travelled to conflict zones in the knowledge they are likely to be criminalising them.

"We absolutely rely on that feed of community intelligence coming into us. I often say, and sadly these numbers are shrinking across policing, that every single cop out there on the street is one of mine.

She had earlier highlighted the sustained increase in counter-terrorism arrests in 2017, which were up 38 per cent on previous years.

"I don't have just a counter terrorism network at my disposal. I have every single community support officer, police officer, police staff member, they're all mine, I might not own them and be able to direct them all the time, but every one of them is mine," she told the World Counter Terror Congress in London.

ACC Nicholson said they are "the crucial link into communities".

She added: "They're the people who can know what's going on, on the ground. Me in my ivory tower at Scotland Yard, maybe I don't know as much [as they do], in fact that's certain.

"Those people out on the streets know more than anybody and we must continue to work really closely and strengthen our communities to a position where they are confident enough to step forward."

Police officer numbers are at a 30-year low, with PCSOs falling to their 2006 level, the latest statistics show.