European Union interior ministers have agreed to draw up plans for the "systematic control" of all people entering the bloc following the disclosure that the mastermind of the Paris terror attacks was able to slip into the country undetected.
French Interior Minister Bernard Cazeneuve said the measure - which would affect everyone crossing the external borders of the travel-free Schengen zone - represented a "crucial" change.
Arriving for emergency talks in Brussels, Home Secretary Theresa May earlier backed French calls to clamp down on illegal arms trafficking and long-delayed measures to gather information on airline passengers.
Amid widespread concerns that extremists are returning from fighting in Syria and Iraq to Europe unchecked, Mr Cazeneuve said further delay was unacceptable.
"We can't take more time. This is urgent," he said. "Terrorists are crossing the borders of the European Union."
The scale of the international Islamist threat has been underlined by an attack by gunmen on an international hotel in the Malian capital Bamako - a former French colony - which left at least three dead, with scores taken hostage.
Meanwhile, French authorities said a third body had been discovered in the wreckage of the flat where Abdelhamid Abaaoud, the extremist believed to be behind the Paris attacks, died in a shoot-out with police on Wednesday.
The prosecutors' office said in a statement that the body is that of a woman but her identity is unclear. Another woman - Abaaoud's cousin Hasna Aitboulahcen - blew herself up with a suicide belt amid the shoot-out.
In Brussels, Mrs May said the Paris attacks, which left 129 dead, underlined the need for improved security across the EU.
"What we have seen is that there was a clear link between security of the EU's external borders and security within the EU," she said.
"I would like to see all member states committed to improving the measures and penalties for dealing with those who traffic in firearms."
The Home Secretary said there also needed to be "immediate progress" on obtaining access to passenger name records.
"The negotiation has taken too long. That must be concluded. The UK will go ahead with obtaining records from those operating to and from the United Kingdom," she said.
Speaking on French television ahead of the meeting, prime minister Manuel Valls said members of the terrorist cell had taken advantage of the "chaos" caused by the refugee crisis to slip into the country undetected.
While Belgium-born Abaaoud, 27, was quickly identified by French investigators as the likely mastermind of the Paris attacks, it was originally thought he had co-ordinated them from Syria where he was fighting with Islamic State.
But on Monday, the French received a tip-off from the intelligence agency of a non-European country that Abaaoud - who had previously boasted of moving between Belgium and Syria unhindered - had managed to cross back into the EU through Greece.
However a senior Greek security official has now insisted there was no record of him passing through the country, which is at the forefront of Europe's immigration crisis, although he could not rule out him having entered on a false passport.