Despite the collapse of the Islamic State's self-proclaimed Caliphate in Iraq and Syria, the international community "cannot turn off the spotlight" on the jihadist group, Italian Foreign Minister Angelino Alfano said on Wednesday.

"The international community has won numerous battles against IS, inflicting very heavy defeats on it which have slashed its territorial hold, prestige and recruiting power.

"But the global coalition against terrorism cannot turn off the spotlight on IS," he told reporters here.

"We need to pay particular attention to the danger that elements of this terrorist organisation survive under other disguises or names, perhaps as common criminals. And we need to keep the movements and destiny of foreign fighters under the spotlight."

Alfano's remarks came a day after Iranian President Hassan Rouhani claimed that IS had been defeated in Syria and Iraq while warning "the remnants will continue".