Hundreds of staff from the UK's financial institutions will take part in a simulated cyberattack today.

The exercise, the details of which have been kept top secret, will be overseen by officials from the Bank of England, Treasury and Financial Conduct Authority, and will be monitored by the Government's cyber agencies.

It will concentrate on how investment banks would cope with a sustained attack on essential shared and company-specific systems, such as clearing and risk management tools.

The cyber war game, called Waking Shark II, will be led by a team from Credit Suisse, who have designed a scenario to be released to the participants in stages, as if the situation is unfolding in real time.

The test will take place in one room, with various companies and organisations sitting on different tables interacting as the situation gathers momentum.

The aim is to help in-house IT security experts and fall-back operations planners to practise making swift decisions and communicate effectively with the regulator and industry partners to contain the problems thrown at them.

The last time such an extensive exercise was undertaken was in 2011, when institutions rehearsed how they would cope with a cyberattack during the busiest period of the London Olympics.

From that, it became apparent that an investment banking-focused exercise would be useful to lay out communication protocols between banking institutions and governing bodies, and to establish who would take the lead to co-ordinate a response in the event of such an attack.

According to David Emm, senior security researcher at internet security firm Kaspersky Lab, the right communication is vital in the aftermath of a cyberattack.

He told Sky News: "Businesses must have a plan of action which includes all relevant stakeholders from both internal and external parties.

"Communication across other sectors can be important as the effects on one company can have far reaching consequences for many others.

"The UK Government is keen to pursue a joined-up approach to dealing with cyberattacks - which is good news, but more work still needs to be done to help all businesses adopt a more secure mindset, and exercises like this help contribute to this."

Results and recommendations from the exercise will be published by early next year.