Terror attacks similar to those that struck New York Sep 11, 2001, are "probably no longer possible", European Union (EU) counter-terrorism coordinator Gilles de Kerchove has said.

"I think we can say today that an attack of the scale and the sophistication that we once had on September 11 probably is no longer possible," de Kerchove was quoted as saying by Xinhua.

However, he stressed: "That doesn't mean we are completely out of threat."

He said Al Qaeda, the terrorist outfit that masterminded the Sep 11 attacks, has been "significantly weakened" by the campaigns in Afghanistan and Pakistan, which also led to the death of its founder Osama bin Laden.

He warned that the terrorist threat of today was "more complex and diverse", referring to remnants of the Al Qaeda in the Arabian peninsula and North Africa.

In the last decade, international cooperation on the war against terrorism has been strengthened by sharing data, collaborating with police and judiciary, Kerchove said.

"Overall, we are much better equipped today that we were 10 years ago," he said.