U.N. Secretary-General Ban Ki-moon says the world needs to focus more on the root causes of terrorism, saying "when you have to counter terrorism, it's too late."

The U.N. chief said the Islamic State group and other radical groups "are now spreading like a cancer around the world."

Ban spoke to reporters Friday near the end of a Swiss- and U.N.-sponsored conference in Geneva on countering violent extremism, which can develop into terrorism Officials say the two-day meeting is the U.N.'s first of its kind focusing on upstream terrorism prevention.

"Of course, 15 years ago there were terrorist attacks," Ban said, "but not as often, not as many, not as widely spread like this."

He alluded to aspects like alienated, jobless youth; violence against women; and technological know-how of extremists.