France has reimposed border controls with its European Union neighbours in response to the threat of attacks after the London bombings.
Passports and vehicles could now be checked at border
The move activates a safety clause of the Schengen open-border agreement between many EU countries.
Interior Minister Nicolas Sarkozy announced the measure after meeting EU counterparts in Brussels.
"If we don't reinforce border controls when around 50 people die in London, I don't know when I would," he said.
Following the move by France, Italy's Interior Minister Giuseppe Pisanu announced that his country would be reinforcing its old border zones with Austria and Slovenia, Efe reports.
France has activated the safety clause before, mainly for major political and sporting events.
The Schengen agreement allows people to travel without checks from country to country.
The agreement emerged outside the framework of the EU and was initially signed by Belgium, France, Germany, Luxembourg and the Netherlands in 1985.
Mr Sarkozy said restoring borders was France's decision, but it had informed other Schengen countries before taking action.
"I cannot ignore that after New York was Madrid, followed by London. I don't know who will be next on the list. But I do know that it is our duty to prepare ourselves so we leave nothing to chance," Efe quoted him as saying.
UK Home Secretary Charles Clarke was chairing the meeting of interior ministers, called after the London bombs, which aims to discuss new measures against terrorism.
EU interior ministers gathered for a similar summit after the 11 March Madrid bombings last year, which killed 191 people.
That meeting led to the faster implementation of the European Arrest Warrant and boosted the sharing of police information to thwart future attacks.
However, proposals to force European phone companies and internet service providers to keep records of the contents of calls and messages have led to concerns over civil liberties.
Italian MEP Lilli Gruber said: "Once you are monitored with your private telephone calls, telephone messages and private e-mails, this is a police state."