A departure from the European Union would have negative consequences for Britain's security, the chief of the bloc's police agency said Monday.
British voters will go to the polls on June 23 to decide whether their country should remain in the EU.
If they vote in favour of Brexit - the buzzword coined for a British departure from the EU after more than 40 years of membership - this would also end the country's membership in Europol.
The British police depends on cooperation with the EU in the fight against terrorism and international organized crime, Europol chief Robert Wainwright said in The Hague.
Taking this away would leave a "big" security "hole," he added.
The British police has played a leading role in European cooperation over the last 40 years, said Wainwright, who is British.
"If you take this infrastructure away, the UK's job to protect its citizens from terror and organized crime will be harder," he noted.