Assistant Commissioner Mark Rowley, the national lead for Counter Terrorism Policing
Assistant Commissioner Mark Rowley, the national lead for Counter Terrorism Policing MET police

British security services have thwarted 13 potential terrorist attacks in the country since 2013. UK's most senior counter terrorism officer also said that at any one time, the services are tackling more than 500 live terror investigations.

In addition, investigators have been making arrests at a rate of close to one a day since 2014.

The official threat level for international terrorism has been at severe, meaning that an attack is "highly likely" for more than two years, the BBC reports..

Mark Rowley, Scotland Yard's assistant commissioner disclosed the figures when he launched the Action Counters Terrorism, an appeal for the public to report their suspicions.

He said that the public's contribution in the past as "extraordinary" and "some of that information is a change in someone's behaviour, some of that's about suspicious activity."

Rowley added: "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."

Information from the public has also helped in stopping some of the 13 attacks, he said.

In urging people to report their suspicions, he said: "If it turns out to be a call where you made it with good intent, but actually there was no problem at the end of it, that's fine.

"We'd rather have many calls like that, rather than miss out on the critical one that helps us stop an attack," he explained.

As part of the campaign, a podcast has been been produced to show how terrorist attacks in the UK were foiled. It features accounts from detectives, bomb disposal and surveillance officers, BBC reports.

Rowley said the idea of releasing the podcast was to show the public how terrorists might prepare and encourage the public to report any suspicions.

In the year to March, the anti-terrorist hotline received more than twice the number of calls compared with the previous 12 months, with 22,000 people calling in. Information from the public has helped police in one third of the most high-risk investigations, figures indicatge.

Rowley said that police face a range of threats and challenges, ranging from encrypted communication methods, propaganda and various possible attack methods.

"Now we worry about everything from fairly simple attacks with knives or using vehicles all the way through to the more complex firearms attacks. All of that mean that our job remains difficult," he said.

Muslim converts 4 times more likely to become terrorist than those born Muslims

According to a study by Henry Jackson Society think tank of Britain's Islamist terrorism, those who convert to Islam are four times more likely to become terrorists than those who were born Muslims.

In addition, brainwashed recruits can take as little as four months from converting into the religion to commit terrorism offences, the study reveals.

The study revealed that London and Birmingham were the main sources of terrorists, with the poorer areas and places facing religious segregation being particularly at risk.

One in 10 of all terrorists in Britain were form five council wards in Birmingham - more than West Yorkshire, Greater Manchester and Lancashire put together, The Times reports.

In addition, women were being used more often , with most of them working u in support of male relatives, friends or associates. Female involvement in terrorism has nearly trebled in recent years, the report showed.

The study by the think tank analyses Islamist-inspired terrorism between 1998 and 2015, which covers 264 individual convictions and five suicide bombers.