MI5 boss warns that foreign spies are using fake profiles on social media sites like LinkedIn to target 10,000 UK officials with access to sensitive material and sites

• Ken McCallum said that fake accounts were being used on an 'industrial 'scale' 
• New campaign by The Centre for the Protection of National Infrastructure 
• 'Think before you link' campaign aimed at people working in sensitive sectors

Foreign spies have used social media platforms like LinkedIn to target 10,000 officials in the UK and abroad who have access to sensitive information and locations, the head of MI5 warns today.

Ken McCallum said that fake accounts were being used on an 'industrial 'scale' in an attempt to steal state secrets.

The Centre for the Protection of National Infrastructure (CPNI), which is part of MI5, said that the 10,000 figure, which covers the past five years, was likely to be a conservative estimate. 

Targets include people working in defence and security sectors, civil servants, pharmaceuticals  and other sensitive industries.

The CPNI is running a 'think before you link' campaign aimed at people working in these areas. 

Launching the campaign, Mr McCallum, who became the director general of MI5 last year, told the Times: 'Malicious profiles on professional networking sites are being utilised on an industrial scale'.

'This campaign, which harnesses the insight derived from our intelligence, behavioural science experts and co-operation of Five Eyes partners, will strengthen the UK’s collective defences against this activity.' 

In a statement LinkedIn said: 'We welcome the online safety efforts of the Centre for the Protection of National Infrastructure and its work to expand their Think Before You Link campaign in the United Kingdom. 

'Teams at LinkedIn work to keep LinkedIn a safe place where real people can connect with professionals they know and trust.

'We actively seek out signs of state sponsored activity on the platform and quickly take action against bad actors in order to protect our members.

'Our Threat Intelligence team removes fake accounts using information we uncover and intelligence from a variety of sources, including government agencies. 

'Our teams utilize multiple automated techniques, coupled with human reviews and member reporting to maintain LinkedIn as a safe and trusted platform. And we enforce our policies, which are very clear: fraudulent activity with an intent to mislead or lie to our members is a violation of our terms of service.' 

It comes as the UK attempts to take a harder line with Russia and China over spying.

On Monday it was revealed foreign spies operating in Britain will be prosecuted and deported under new laws to protect the country from hostile states.

The Queen’s Speech on May 11 will reportedly be used by the Prime Minister to announce a bill outlining measures to protect Britain from the likes of Russia and China.

It will mandate that all individuals working on behalf of foreign governments in the country will have to register their presence - not doing so will become a criminal offence, The Times reported.

 Intelligence agencies have warned that under current laws, foreign spies are immune from the law unless they are caught acquiring official secrets.

It is believed that Britain will aim to have a similar register to the Foreign Agents Registration Act in the US, which extends to anyone representing the interests of a foreign state.

The Official Secrets Act, which is intended to protect the United Kingdom from espionage, will be updated so it can be used against anyone attempting to undermine Britain’s interest from abroad.

With some parts written in 1911, ministers hope to adjust the legislation so it can be used against those carrying out foreign cyberattacks.

They are also considering whether to raise the maximum sentence - which is currently two years for most offences - for any breaches of the act.

It comes after Foreign Secretary Dominic Raab said Britain stood in 'full support' of Czech government after the country's police confirmed they were searching for two men who were suspects in the Salisbury novichok attack.

The Czech Republic is expelling 18 Russian diplomats it has identified as spies in a case related to an explosion at an ammunition depot in the town of Vrbetice in 2014.