The terminal building at Luton Airport, north of London, has been reopened after it was evacuated earlier when a suspicious item was found.
All incoming flights were suspended and the approach road to the airport was closed.
Bedfordshire Police said that they had cleared the departure lounge at Luton, the Britain's sixth biggest airport, which primarily serves holiday destinations.
The police said they have now successfully concluded their investigation inside the terminal and have confirmed the airport is now safe for normal operations to resume.
Airport staff are working to re-open the terminal and get flights moving as soon as possible.
Passengers were advised to contact their airlines for the latest flight information.
The UK recently raised its international terrorism alert to its second-highest level, saying Islamic State in Syria and Iraq posed the country's greatest-ever security risk.