With Britons on alert and security beefed up at transport hubs over a suspected al-Qaeda plot against Britain, thousands of passengers were evacuated from Terminal 4 at London's Heathrow Airport on Tuesday as police investigated a suspicious package.
The terminal reopened later but British Airways said it was forced to cancel 108 flights to the United States and Europe.
Britain's security threat level has been set at "critical" following the three foiled terror plots.
During a parliament session, Prime Minister Gordon Brown praised security services and Britons for their handling of the crisis.
