Cameron announces hundreds more armed police officers to counter terrorism threat

The move comes after a UK Government review of the capacity and capability of police forces to act in the event of "complex" attacks, similar to that on Charlie Hebdo or the simultaneous strikes launched in Paris in November.

As yet, there has been no equivalent announcement in Scotland.

Last week, the Scottish Police Federation, a staff association representing rank and file officers, reiterated warnings it made in the wake of the Paris attacks that Scotland was "woefully under-equipped, under-resourced and underprepared" to deal with a similar incident.

Speaking at the weekend, Assistant Chief Constable Ruaraidh Nicolson, who is responsible for counter-terrorism in Scotland, said the nature of any terror attack north of the border was unlikely to be as "sophisticated" as those in Paris because of the relative difficulty of getting firearms.

Asked about where the threat would come from, Mr Nicolson replied: "It's going to be from people who are already in the country. That's likely not to be the kind of firearms capability we've seen in Paris because we believe the profile of firearms in Scotland is much lower. It's much more likely to be an unsophisticated attack."

The Prime Minister made his announcement as he attended a summit in Washington, where world leaders are discussing plans to protect nuclear facilities.

He said: "Our police and intelligence agencies work round the clock to keep us safe and it is absolutely vital that we support them with the right resources and kit.

"After the terrorist attacks in France last year, we decided to look at whether there was more we could do to protect people from the type of terrorist threat we now face.

"That's why we are increasing the number of specially trained armed officers up and down the country to make sure the police have greater capability to respond swiftly and effectively should they need to do so."

No 10 said the beefed-up network of armed police units was intended to complement military contingency plans already in place to deploy up to 10,000 troops in the event of a terror attack.

Soldiers would be drafted in to assist with the broader security response and relieve armed police guards, who can in turn respond to incidents.

The recruitment drive aims to have 1000 more armed police in place across England and Wales by spring 2018 with 400 ready to be deployed to cities including Manchester and Birmingham.

It includes plans to have 600 extra armed police officers in London which were announced in January.

An additional 40 armed response vehicles and teams are due to be "up and running" within the next 12 months, bringing the total number south of the border to 150. London will see its fleet doubled.

The vehicles are adapted so the armed officers can be deployed along with their specialist kit to incidents at speed.

Funding for the increase will come from the £143 million set aside in the Strategic Security and Defence Review to increase armed response capability and capacity.

Simon Chesterman, the National Police Chiefs' Council lead for Armed Policing, said: "This additional uplift will ensure we are in an even stronger position to respond quickly and effectively to protect the public."

Meantime, Mr Cameron has warned that terrorists will use "whatever materials they can get their hands on"as world leaders gathered to discuss the security of nuclear facilities.

The PM said terrorists would "like to kill as many people as they possibly could" amid fears Islamic State jihadists could attempt to create a dirty bomb.

The UK and the US are to take part in a joint exercise next year to prepare for any online attack against nuclear power plants and waste storage facilities.

Mr Cameron is to offer British expertise to other countries to safeguard their own civil nuclear installations.

Speaking in Washington, where Barack Obama is hosting the Nuclear Security Summit(NSS), the PM said: "We know that the terrorists we face today would like to kill as many people as they possibly could, using whatever materials they can get their hands on.

"So obviously the security of nuclear materials, for those countries that have nuclear programmes, is incredibly important and that's why this conference like previous conferences will make sure that we have proper security for those materials, not just in Britain - we are quite a global leader in this - but also all over the world.

"So it's a very important subject, there will be very important actions announced at this conference, and it's about making sure our world is safe and secure and we are not at risk from terrorists coming together with nuclear materials."

The attacks in Brussels have raised fresh concerns about the prospect of nuclear terrorism.

Belgian media reported that two of the suicide bombers in the attacks, brothers Ibrahim and Khalid El Bakraoui, had video footage of the home of a senior official at a Flanders nuclear waste facility.

A UK Government source said there was no "credible evidence" that terrorists were targeting British facilities.

But the cyber attack exercise with the US would ensure that both governments and their civil nuclear industries were prepared and could address any potential weaknesses.

The source said: "You saw just last week in Belgium concerns that were raised around the security of civil nuclear sites and therefore, in the world in which we currently live, we think it's the right thing to do."

As the summit opened, the US said a strengthened nuclear security agreement among nations was finally set to take force following ratification by a critical mass of countries.

The stricter rules include new criminal penalties for smuggling nuclear material and expanded requirements for securing materials and nuclear facilities worldwide, and are intended to reduce the likelihood of terrorists getting their hands on ingredients for a bomb.

However, doubt has been raised about the effectiveness of the summit and its decisions given the event is being boycotted by Vladimir Putin, the President of Russia, which, together with the US account for more than 90 per cent of all the world’s nuclear weapons.

The summit will conclude later today with world leaders taking part in a "scenario-based session" focusing on the "threat from nuclear terrorism".