UNITED NATIONS, United States (AFP) - Despite defeats in Iraq and Syria, the Islamic State group (ISIS) has reorganised and is now "more focused than ever" on attacking Europe and other areas outside that conflict zone, a senior UN official said Thursday.

"ISIL, despite continuous military pressure, continues to resist, particularly in Mosul and Raqa," said UN Under-Secretary-General for Political Affairs Jeffrey Feltman, using another acronym for ISIS.

"At the same time, ISIL has reorganised its military structure, giving more power to local commanders and is more focused than ever before on enabling and inspiring attacks outside of conflict zones."

Speaking before the UN Security Council, Feltman cited recent attacks in Belgium, Britain, France, Germany, Russia, Sweden and Turkey.

The group has posted fewer messages on social networks in the past 16 months, but "the threat persists as supporters outside Syria and Iraq collect and redistribute this propaganda."

The total number of ISIS fighters and the group's revenues have also dropped during the same period, Feltman added.

But ISIS can count on tens of millions of dollars a month from oil sales, extortion, ransom kidnapping, antiquities trafficking and mining exploitation in territories they control.

While the number of foreign fighters recruited by ISIS has also decreased, "returnees and the relocation of fighters from the conflict zones to other regions now present a considerable threat to international peace," Feltman said.

He called for reinforced ties between the UN system and regional actors to support Sahel G5 states - Burkina Faso, Chad, Mali, Mauritania and Niger - in their counterterrorism efforts.

On Tuesday, France asked the UN Security Council to authorise the deployment of a five-nation African military force to fight violent extremists and drug traffickers in the Sahel.

The Sahel G5 states agreed in March to set up the special counter-terrorism operation of 5,000 troops for the region.

"It is important that the Security Council gets united behind this draft," French Ambassador Francois Delattre said.

"Again, on terrorism, there is no place for disunion. So we cannot imagine that the council doesn't bring its full support behind our draft."

Diplomats say the United States has resisted financing this force during initial discussions.