The U.K. will no longer have access to multiple databases critical for combating transnational crime and terrorism after January 1 because it has thus far failed to come to a Brexit agreement with European security agencies and regulators on the use of collected data.

The situation, according to EU intelligence officials, will force security officials on both sides of the channel to work much harder and less efficiently to check names, passports, travel history, criminal records, and other investigative tools to track suspects moving around Europe and between the EU and the United Kingdom.

“The Schengen system alone is accessed over 500 million times a year by U.K. officials, but tomorrow the daily average of 1.6 million requests for information will stop and U.K. officials will be forced to collect all the information from other sources,” said a senior Belgian counter-terrorism official, whose service does not allow them to speak openly to the media.

“This information can certainly be found but the point of these systems and databases is speed and proper managing of huge streams of information.”

The “Schengen” area refers to the 26 European countries which have abolished all border controls.

Brexit Will Hurt Investigations and Prevention of Organized Crime and Terrorism, Security Officials Say.

Two senior European counter-terrorism officials told Insider that the U.K. exit agreement’s failure to include access to the Europol systems for tracking wanted fugitives and international arrest warrants would hurt investigations and prevention of organized crime and terrorism until a new agreement was reached. The European system combines Interpol’s international system with the EU’s criminal databases, as well as the extensive database of all Schengen area travelers.

“It’s rather demoralizing because in the case of the Schengen database this was a project that all EU member states have worked on closely since 2015 to close gaps in the system that were revealed in terror attacks from 2014 until 2016,” said the Belgian official. The source had investigated the November 2015 attacks in Paris as well as the March 2016 attacks in Brussels by a cell of Belgian ISIS members.

After the Paris attacks, which killed 137 people in multiple incidents including the Bataclan nightclub, EU officials were aghast to learn that the European terrorist planners had been known to law enforcement as ISIS members and had been able to return to Europe from Syria unnoticed by hiding within the huge refugee flows to Europe at the time.

“The Molenbeek cell investigation covered all of Europe, from refugees coming through the Balkans via Greece, to suspected financial support from jihadis in the U.K., to movements throughout all Schengen member states and the U.K. and Norway,” said the official about the scope of the Bataclan investigation.

“We discovered how terrorists and criminals could use holes in the system to move freely once they arrived inside Europe and spent five years and millions of Euros fixing this system the best we could and now after all that work, the U.K. has walked away from the effort.”

The UK Is Good at Generating Terrorists.

A French law enforcement source, who works directly on vetting travelers entering Schengen through France, said that the U.K. would be able to replicate most of the system eventually but at a huge cost of efficiency until a fuller system can be developed.

The official also noted what they described as the British government’s refusal to accept that most U.K. terrorism is generated internally, in terms of networks and cells. The U.K. generates many of its own terrorists and is often as much a vector of terrorism as a victim.

“The irony of the Brits wanting to get away from European regulators by adopting several new layers of bureaucratic regulations that will be required whenever they want to check if someone is a terrorist, is unsettling because it affects us as well,” said the police source, who works undercover and cannot be named.

“The Only Country in Europe With as Many Active Terrorists as France Is the UK”

“The only country in Europe with as many active terrorists as France is the U.K.,” said the police official.

“People talked during Brexit about controlling their borders, OK, fine. But the U.K. did control its own borders, its participation in the Europol and Schengen databases was necessary in large part to protect Europe from British terrorists… there are more attacks in Europe by jihadists with links to the U.K. than there ever have been attacks in the U.K. linked to Europe. France has this problem as well — our people have been involved in attacks around Europe. And remember Bataclan was led by Belgians, not French. This is why we are serious about international cooperation: Yes, we want to keep France safe but we are also obligated to keep the rest of the world safe from French terrorists.”

“The British are in the same situation as France,” in terms of the internal terror threat, said the French official. “But, at least for now, they have chosen to make it more difficult and time-consuming to fight terrorism anywhere.”

This article was written by Mitch Prothero and originally published on Business Insider.