Paris attacks: Europe on high security alert
Eight alleged members of so-called Islamic State (IS) have been arrested, Turkish officials have said amid security concerns across Europe.
The men, all Moroccan, are suspected to have been travelling to Germany when they were arrested at Istanbul airport.
It comes a day after Germany decided to call off Tuesday night's football match with the Netherlands in Hanover because of security fears.
Europe has been on high alert since attacks in Paris killed 129 people.
Turkish officials told the BBC's Mark Lowen the eight men were on a list of those banned from entering Turkey.
They were arrested after arriving at Istanbul airport on a flight from Casablanca.
The men claimed that they had a hotel reservation in Istanbul, which proved to be false, officials said.
Turkey - long accused of taking a soft approach towards IS, say correspondents - is now stepping up the fight, taking a more active role in the US-led coalition.
Only a day before Germany cancelled a football match with the Netherlands in Hanover.
The city's police chief said they had "received specific indications that an attack with explosives was planned".
German Chancellor Angela Merkel has defended the decision. She said on Wednesday that finding the balance between "liberty and security" was difficult, but "it was decided, correctly, to err on the side of caution".
Germany's national football team was playing France at the Stade de France in Paris when it was targeted by suicide bombers on Friday night as part of a wave of attacks across the city.
No civilians died in the stadium attack, but 129 people died and more than 400 were wounded elsewhere.
In the wake of the Paris attacks, numerous European countries have heightened security measures:
- A bomb scare at Copenhagen's international airport prompted an hour-long evacuation of hundreds of passengers. Danish police said on Twitter it was "an overheard conversation about a bomb'' that lead to the evacuation. Commuter train and subway lines were also were briefly suspended. The threat was found to be a false alarm
- Sweden's security service says it has raised the Scandinavian country's terror alert to the second-highest level. Denmark has done the same
- There has been a visible increase in security around the Vatican ahead of Pope Francis's big Jubilee Year, which opens on 8 December. Italy has announced it will close the airspace over Rome to drones during the celebrations, which are expected to draw millions of pilgrims. Some 700 additional troops have also been deployed in public spaces in Rome.
- The Slovak government is planning to tighten anti-terrorist legislation following the attacks in Paris. Prime Minister Robert Fico said on Wednesday that changes to anti-terror laws should be discussed by his government next week.