Emergency measures to relocate tens of thousands of people working in London are being drawn up in response to the 11 September attacks on the United States.
The evacuation plans for staff in the financial sector are being developed in case a nuclear, biological, or bombing assault is launched on the capital. Details of the initiative became public the day after the financial watchdog, the Financial Services Authority (FSA), announced it had set up a secret emergency centre to ensure markets could continue to operate after a large-scale strike by terrorists.
The plans to evacuate parts of London within hours of a crisis were disclosed in a letter by Judith Mayhew, the chairwoman of the City of London Corporation's policy and resources committee, to the Commons Defence Committee as part of an inquiry into civil emergency preparations.
Since the 11 September attacks on New York and Washington, authorities and emergency services in the City have been reviewing the capital's plans to deal with a terrorist incident.
Ms Mayhew told the MPs in her letter: "London is currently looking at methods of mass evacuation in certain geographical areas. This requires very precise communication methods as does the message allowing the return of those evacuated." She suggests that warnings and instructions for evacuation should be put out on television and radio.
Ms Mayhew said yesterday that the evacuation would be aimed at the 350,000 workers based in the City of London's square mile – Britain's financial centre – and tens of thousands at other financial institutions in the Docklands area, including Canary Wharf, in east London.
The majority of those in the evacuation would be taken to rendezvous points, while small groups would walk to back-up offices fitted with computers and food supplies that would allow the financial markets and banking to continue to operate.
The FSA has just set up a suite of offices at a secret location close to its headquarters in Canary Wharf where 30 staff will be able to continue to work with the help of the regulators. The emergency measures have been drawn up by a group that includes representatives from the Bank of England, the Treasury, the FSA and the Corporation of London, which is the local authority for the City area.
Plans for a London-wide response to a terrorist attack are also being developed. Since 11 September a special civil contingencies committee for London has been reporting to emergency planners in Whitehall. Health authorities in the capital have also been stockpiling supplies of anti- radiation pills in case of widespread contamination by a nuclear device.
Security sources have stressed that no specific intelligence suggests Britain has been chosen as a target by supporters of al-Qa'ida but the country's close ties with the United States have made it vulnerable.
Ms Mayhew said: "The attacks on 11 September made us realise how closely linked we are to New York. In the run-up to the anniversary of 11 September we are urging people to have another look at their contingency plans."
The regulator warned that, while the larger financial institutions were prepared for an evacuation and had established back-up centres with alternative supplies of power and telecommunications, many smaller companies in the City had not bothered to take any action.