London's Gatwick Airport evacuated its North Terminal on Saturday due to "an incident", hours after a string of attacks in Paris claimed by the Islamic State group killed 128 people.
"Due to an incident -- the North Terminal has been evacuated as a precautionary measure," said the airport's official Twitter account.
"Extra staff are on site looking after passenger welfare."
Sussex police later confirmed they were dealing with a "suspect package".
Gatwick is one of Britain's busiest airports, handling 39 million passengers travelling to 200 destinations every year.
British security services are on high alert following the suspected attacks on a rock concert, restaurants and national football stadium.
Britain's Foreign Office earlier updated its travel advice for British nationals in France, urging them to "exercise caution in public places and follow the advice of the local authorities".
Eurostar services between London and Paris were running as usual on Saturday, despite initial concerns that French borders would be closed following the attack.