THE head of Scotland’s anti-terror squad has revealed that police are actively tracking groups of Islamic extremists north of the border.

Assistant Chief Constable Ruaraidh Nicolson said his officers are keeping close watch on “pockets” of suspects feared to be planning terrorist offences in Scotland. Leading members of Scotland’s Muslim community also expressed fears about the risks of radicalisation.

The head of organised crime and counter terrorism for Police Scotland spoke out about security in Scotland after terrorists linked to the so-called Islamic State group detonated suicide bombs in Brussels which claimed the lives of 31 people.

Nicolson warned that a similar attack “could happen anywhere” but insisted the community engagement approach employed by his officers means the risk is less likely in Scotland.

Despite this, several young Scots have been radicalised by Islamic extremists in recent years. Would-be terrorist Mohammed Atif Siddique, of Alva in Clackmannanshire, was jailed for eight years for terror offences in 2007. Glasgow schoolgirl Aqsa Mahmood became known as the “Jihadi bride” after travelling to Syria to marry a militant in 2013. And Abdul Rakib Amin - who moved to Scotland with his family when he was ten-years-old and was schooled in Aberdeen - appeared in an IS recruitment video before he was killed in an RAF drone strike in August last year.

Meanwhile, there are fresh concerns about the threat of radicalism at Glasgow Central Mosque after it emerged that imam Habib ur Rehman praised Islamist assassin Mumtaz Qadri as a “true Muslim” and equated his actions with the French resistance against the Nazis during World War Two. Yesterday, he apologised "unreservedly" for any offence, a Mosque spokesman said.

Nicolson said: “Of course we’ll have pockets [of extremists] like everywhere else...It is something we monitor and we make sure it doesn’t manifest itself into causing difficulty which we need to stamp out at every opportunity.

“My task is to look across the whole of Scotland. It would be easy to say that in the population densities we’d have more...but the important thing is knowing and understanding what’s going on and actually having interventions where we need to have interventions.”

Human rights lawyer Aamer Anwar, who acted for the family of Aqsa Mahmood and has spoken out against conservative elements at Glasgow Central Mosque, warned that more young people in Scotland could be radicalised.

He said: “I don’t think there’s any ifs or buts about it. I don’t think the community can hide from the fact the potential is there. The way I’ve always viewed it is all that’s required is for one individual to be radicalised. And we’ve already seen a handful of individuals radicalised.

“It’s easy enough for a handful of individuals to carry out mass mayhem. That’s more than enough to cause maximum damage, to destroy social cohesion, to create a backlash against the Muslim community, to divide us.

“Clearly there’s a potential for that and the security services do have people under watch and have concerns.

“We have individuals in our communities, right across this country. If anyone denies that there are individuals in Scotland then how is it that Aqsa Mahmood left for Syria?

“It could be ten or twenty people but that doesn’t really matter because the way they will see it is they only need to be successful once.”

Scottish Labour’s justice spokesman, Graeme Pearson, a former senior police officer and ex Director General of the Scottish Crime and Drug Enforcement Agency, also raised concerns about radicalised Scots.

He said: “I would be loath to call them home-grown extremists but I think we will have disaffected people in our communities. We’ll have people who might be unbalanced in their view of what society is about.

“One would hope that security services and Police Scotland have the necessary intelligence to identify that type of person and ensure that their movements are properly monitored and any real threat is dealt with at an early stage.”

He added: “Only a fool would say a terror attack like that which happened in Brussels wouldn’t happen here, but I think we have the kind of communities we can trust. I think we’ve got the kind of services that are professional. If it’s humanely possible to identify a threat beforehand, it’s most likely it could be done here in Scotland as anywhere.”

Police Scotland, like the rest of UK security and law enforcement, is operating at a “severe” threat level, meaning an attack is “highly likely”.

Home Secretary Theresa May has said seven terrorist plots to attack the UK have been disrupted in the last eighteen months. She also confirmed that around 800 “people of interest” to the security and intelligence agencies have travelled to Syria and Iraq from the UK, including women and families.

Nicolson would not reveal whether his team had foiled any terror plots in Scotland. He also refused to discuss the number of people under surveillance.

“I’m not going to talk directly about plots and cells,” he said.

However he was keen to offer reassurances that everything is being done to prevent a terrorist attack in Scotland. Officers staged a mock firearms incident at Braehead shopping centre in Glasgow earlier in the year to sharpen the response to such a threat.

Nicolson said: “It could happen anywhere but there’s work we’re doing on a day to basis to ensure, as best we can, that doesn’t happen in Scotland.

“We’re working with local communities and we’re engaged from an intelligence and information perspective, not only in Scotland but also more broadly in the UK and wider than that so that we’ve got a real understanding of exactly what’s going on in Scotland...Obviously we’re at the same threat level as the rest of the UK. However, we don’t have any intelligence about imminent attack planning in Scotland.

“We continue to monitor that to make sure that it stays that way. We’ll react to any information and any intelligence that come in and we will make sure that if we see anything develop we’ll nip it in the bud.”

SNP MP Stephen Gethins, who is the party’s Europe spokesman and a member of the House of Commons Foreign Affairs Committee, welcomed reassurances offered by Nicolson.

He said: “There is absolutely no room for complacency. We always have to remember the tragedies that fell on the streets of Brussels this week and in Paris a few short months ago could happen anywhere. London and Glasgow know only too well of that bitter experience.

“The conflict is Syria is having ramifications well beyond that country’s borders and clearly poses a threat to Western Europe. It’s more important than ever before that authorities across the United Kingdom work together on this threat and countering extremism.

“That also means ensuring that we have a strategy for tackling the threat online, in local communities and on a national level.”

A spokesman for Glasgow Central Mosque said: "Mosques and Islamic centres continue their essential work of education and promotion of community cohesion within Scotland which is key to preventing radicalisation, extremism and terrorism.

"The Muslim community is determined to continue their vital role working with partners such as Police Scotland, local authorities, and other faiths in building a better Scotland during very challenging times."

Mohammed Siddique – clarification

On 27 March , we carried a report under the heading “Anti-terror chief: Islamic extremists in Scotland now being tracked”.  It mentioned the conviction of Mohammed Siddique on terrorism charges in 2007. We have been asked to highlight that his  conviction on one of the charges was quashed by his successful appeal in 2010, and Mr Siddique was released from prison, though two other charges relating to terrorism were unaffected.