The head of the European Union police agency voiced concern about the possibility of a militant attack on the European soccer championship scheduled in Paris in June, calling the event "an attractive target for terrorists".

Europol chief Rob Wainwright told the German newspaper Die Welt that European authorities had braced for potential attacks long before the Islamic State bombings and militant attacks in Brussels and Paris, and Euro 2016 was no exception.

"It is shockingly easy to attack soft targets like cafes, restaurants or a concert hall," Wainwright told the newspaper in an interview published on Saturday.

"I am extremely concerned about the upcoming European soccer championship. It is an attractive target for terrorists."

France announced last month that it plans to extend the state of emergency in place since November's attacks on Paris by two months, to maintain security through the Euro 2016 soccer tournament.

Euro 2016 starts June 10 and runs for a month at 10 stadiums around France. Some 2.5 million spectators are expected for 51 matches involving 24 teams. There will also be fan zones for crowds of TV viewers in major cities.

Wainwright said increases in the numbers and equipment of counterterrorism units were "absolutely necessary" to respond to the growing threat of militant attacks.

"We need police units that can respond to attack scenarios and hostage situations like those seen in the Bataclan concert hall in Paris," he told the German daily. Islamic State militants killed 130 people in attacks in Paris last November, most of them inside the Bataclan during a rock concert.-Reuters