A series of bomb blasts have ripped through central London causing widespread disruption and chaos.
The first explosions went off on the London tube network during the height of the rush hour. Police say they know of four explosions affecting Aldgate East, Edgware Road, King's Cross, Liverpool Street, Moorgate and Russell Square. At least one of the explosions ripped apart a packed double decker bus in the Tavistock Square area in a suspected suicide bomb attack.
Police spokesmen have confirmed multiple fatalities and hundreds of injuries.
By 10.00am, the London Emergency Plan had swung into action. All public transport in and out of London ground to a halt and telecommunications networks were disabled. Mobile phone networks started coming back onstream around mid-day.
Financial services companies initiated well-rehearsed disaster recovery procedures, shifting order volume to overseas desks and evacuating staff from affected areas.
Swiss bank UBS cleared its London foreign exchange and fixed income dealing rooms at 100 Liverpool Street as news of the attacks swept markets. Other brokers in the Liverpool Street area followed suit.
"Spot FX volumes have dried up because we've got... major players who have evacuated their dealing rooms," a UBS trader told Reuters.
London Clearing House evacuated its offices from Aldgate and matches were halted before resuming at a back-up site. The London Stock Exchange continued trading throughout the day.
At 10.45 am, the FTSE 100 index was 126.4 points lower at 5,103.2, having earlier reached a low of 5,069.2 as news of the explosions filtered through. By early afternoon the index had recovered some of its poise and was trading just 100 points down on the previous day's close.