Following the terrorist attacks in New York in 2001, the Treasury has been consulting on plans, should the same happen in the UK.
The consultation is proposing to allow the Treasury to take over the running of London's financial markets and suspend the markets and any trading, if it becomes necessary. This would mean the stock market closing for a period and investors not being allowed to trade.
Ruth Kelly, the Financial Secretary to the Treasury said "it is vitally important that there are arrangements in place to maintain the financial system's resilience during operational disruption'. Disruptions could also spread from natural disasters and computer viruses.
Any proposals to be introduced would be through the civil contingencies bill and then debated before being put before Parliament.