British Airways today canceled all flights from London's Heathrow and Gatwick airports scheduled till 6 PM-UK time due to a global computer outage.<br/><br/>The Airline said a major IT system failure is causing very severe disruption to its flight operations worldwide. Airlines, aircraft landing at Heathrow are unable to park up as outbound aircraft cannot vacate the gates, which has resulted in passengers being stuck on aircraft.<br/><br/>Delays have also been reported in Rome, Prague, Milan, Stockholm and Malaga due to the system failure. The company has refuted media claims that the outage had been caused by a cyber attack, saying that there was no evidence to support the claim.