Last checked at 
By Huw Jones and Steve Slater
LONDON, Nov 7 (Reuters) - Thousands of staff across dozensof London financial firms will be put through a "war games"scenario on Tuesday to test how well they can handle a majorcyber attack, people familiar with the matter said.
In one of the largest exercises of its kind in the world,the test dubbed "Waking Shark II" will bombard firms with aseries of announcements and scenarios, such as how a majorattack on computer systems might hit stock exchanges and unfoldon social media.
It will be co-ordinated from a single room housingregulators, government officials and staff from banks and otherfinancial firms, people familiar with the matter said.
Hundreds more people are expected to be involved from theirown offices as the "war game" plays out, they said.
Simulations are likely to include how banks ensure theavailability of cash from ATM machines or deal with a liquiditysqueeze in the wholesale market and how well firms communicateand coordinate with authorities and each other.
There will be a particular focus on investment bankingoperations, one of the sources said.
Regulators and firms are growing increasingly concernedabout the threat of cyber crime to the banking system, includingthe impact of coordinated online assaults or hacking attacks onspecific banks and the Bank of England's Financial PolicyCommittee has already told banks to strengthen defences.
British police arrested eight people in September after acyber attack on the computer system of a branch of Barclays, just a week after 12 men were arrested for allegedlyplanning to steal millions of pounds from a Santander UK branch with a similar remote device.
London is not alone in testing its preparation. New Yorkstaged "Quantum Dawn 2" a few months ago to simulate how firmswould cope with a cyber attack in markets.
Next week's London event will be co-ordinated by the Bank ofEngland, the Treasury and Financial Conduct Authority, andfollows a similar exercise two years ago.
The three regulators declined to comment.
The 2011 event involved "a concerted cyber attack upon thefinancial sector" that disrupted wholesale and retail paymentsand online services and included more than 3,500 people,according to an evaluation published the next year.
Eighty-seven firms were involved, included hedge funds,asset managers and brokers, as well as banks, insurers andexchanges. Representatives from organisations such as the Centrefor the Protection of National Infrastructure (CPNI) and theCyber Security Operations Centre (CSOC) were also involved.
Firms were asked to assume the test was carried out on thebusiest day of the London 2012 Olympic Games, when many staffwould not be in the office.
Next week's test will be the seventh market-wide exercisecarried out by UK authorities to test the resilience of thefinancial industry to a variety of potential shocks.
Past events have included simulated storms, flooding andtransport chaos in 2009 and a flu pandemic in 2006.
A report on the outcome of the test will be released latethis year or early in 2014, one of the sources said.
