Washington (AFP) - The fight against violent extremism is a "third world war" that knows no borders, Jordanian Foreign Minister Nasser Judeh said Thursday, in urging greater international efforts to counter the threat.

Violent extremists groups count foreign fighters from about 90 different countries, "all potential terrorists in their own country when they return," Judeh said during a a three-day conference on combating extremism hosted by President Barack Obama in Washington.

In the wake of brutal attacks in Europe and the Middle East, Obama said earlier that more must be done to prevent groups like Islamic State and Al-Qaeda from recruiting and radicalizing.

"The threat we are confronting today is unprecedented... It recognizes no boundaries, no religion, no culture, no ethnicity. It spares no religion, no culture, no ethnicity," Judeh said.

"These terrorists have proven to have no limit or inhibition to their brutality, barbarism or savagery," he added.

"It's our war as Muslims... It's our collective war as an international community."

He then reprised comments made by Jordan's King Abdullah II in December during a White House visit, labeling the fight against Islamic State militants a "third world war," and pressed for increased international cooperation in the "generational fight."

"Violent extremist groups provide... an umbrella of legitimacy to criminals everywhere," Judeh said, pointing to recent attacks in Copenhagen, Ottawa, Paris and Sydney.

"Each one of us is a target. Let us work together to make them all a collective target."