Originally an offshoot of al Qaeda, IS took large swathes of Iraq and Syria from 2014, creating a theocracy known for beheadings and attacks by supporters in the West - but it was slowly beaten back to the village of Baghouz.

"We announce today the destruction of the so-called Islamic State organization and the end of its ground control in its last pocket in Baghouz," Syrian Democratic Forces (SDF) general commander Mazloum Abdi told a victory ceremony.

SDF fighters, who besieged Baghouz for weeks while planes pounded from above, paraded in memory of 11,000 comrades killed in years of fighting against IS.

A band played the American national anthem.

Despite the euphoria, some shooting and mortar fire continued on Saturday morning, according to a Reuters journalist at Baghouz. And Abdi warned the campaign against the militant's more hidden threats must continue.

Some ISIS fighters still hold out in Syria's remote central desert, and in Iraqi cities they have slipped into the shadows, staging shootings or kidnappings.

The United States believes the group's leader, Abu Bakr al-Baghdadi, is in Iraq. He stood at the pulpit of the medieval mosque in Mosul in 2014 to declare himself caliph, sovereign over all Muslims.

Further afield, jihadists in Afghanistan, Nigeria and elsewhere show no sign of recanting allegiance, and intelligence services say ISIS devotees in the West might plot new attacks.

REUTERS