Wiping out Islamic State group, also referred to ISIS, "will not end" the global threat from jihadi groups, according to a report by the Centre on Religion & Geopolitics -- a think tank run by Tony Blair Faith Foundation.

There are about 15 lesser militias with 65,000 fighters ready to fill the vacuum resulting from a defeat of ISIS in Syria and Iraq by a coalition led by the U.S., the center said, adding that the "West risks making a strategic failure by focusing only on IS. Defeating it militarily will not end global jihadism. We cannot bomb an ideology, but our war is ideological."

According to the report, about 60 percent of fighters in rebel factions in Syria identify with religious or political ideology similar to that of ISIS propagandists. "The greatest danger to the international community is the groups that share the ideology of Isis, but are being ignored in the battle to defeat the group."

Groups including al Qaeda affiliate Jabhat al-Nusra and Ahrar al-Sham could compete for the spotlight to ensure allegiance from the global fighters and financing that ISIS currently attracts, the report said, warning that fewer than a quarter of the rebels surveyed were not ideological.

The western military campaign against ISIS must be accompanied by an "intellectual and theological defeat of the pernicious ideology that drives it", the centre argued.

On Friday, the United Nations Security Council agreed on a peace process that holds the prospect of ending the conflict -- the first time since fighting started in Syria five years ago. However, sharp disagreements reportedly remain to be sorted out between the American and Russian positions.

The U.N. also agreed on a resolution endorsing the start of "urgent" formal negotiations between President Bashar Assad's regime and moderate opposition groups early next month.

While the U.N. resolution made no mention of whether Assad would be allowed to run for the new government, the think tank report said that unless Assad leaves or is removed from office, the war in the country is likely to spread further.