Europol chief Rob Wainwright urged European intelligence agencies and police to work together to stop terrorism as prevention becomes even more difficult.
Speaking to the Today Programme, Mr Wainwright said: “I’ve seen a significant increase in information sharing between countries and agencies but we need to go further.
“The threat has been at the highest level for some time and it’s highly complex in nature.
“We’re dealing with a very diffused community of thousands of radicalised individuals out of which anyone can become a potential terrorist at short notice.”
Mr Wainwright explained the EU is currently promoting a new project which would bring together international criminal databases to help both the police force and the intelligence community.
The civil servant said that such project would allow more people to be monitored for terrorist activity.
Islamic extremists have been heavily targeting European countries since January 2015, when 20 people were killed in a series of attacks in Paris, France.
Earlier this month, another two related attacks shook the holiday hotspot of Barcelona, Spain.
Fifteen people died when a car mowed down the crowd on the busy shopping street of Las Ramblas.
Mr Wainwright also said that, despite the increased collaboration between EU agencies since 2015, there were still issues to address to succeed in the battle against terrorism.
He said: “Not always is anything known about them [the terrorists] in the police records. That is what happened in Barcelona. The police had little to no knowledge about any of the suspects in advance. What it says is that we have
“The police had little to no knowledge about any of the suspects in advance. What it says is that we have to maximise the precious information that we have from all possible sources.”