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.