Final assault on last IS-held pocket in Syria resumes U.S.-backed Syrian forces on Friday resumed military operations to liberate the last piece of territory held by the Islamic state group in Syria after evacuating thousands of civilians and hostages inside, a spokesman said

OUTSIDE BAGHOUZ, Syria -- U.S.-backed Syrian forces on Friday resumed military operations to liberate the last piece of territory held by the Islamic State group in Syria after evacuating thousands of civilians and hostages, a spokesman said.

Mustafa Bali said fighters from the Kurdish-led Syrian Democratic Forces have begun clashing with the militants and advancing after the last batch of civilians left the territory.

"Those left inside are fighters who do not wish to surrender," he told The Associated Press.

The military campaign to uproot the militants from the eastern banks of the Euphrates began in September, pushing them down toward this last corner in the village of Baghouz, near the Iraqi border. The military operation was halted on February 12 after the SDF discovered there was still a large number of civilians and hostages in the territory, which sits atop caves and tunnels where they had been hiding.

Thousands of civilians have been evacuated since then, many of them women and children in desperate conditions. The evacuees said food was running low and clean water and medicine were scarce. Many defended what remained of the extremist group's territorial hold, which once spanned a third of Iraq and Syria.

As they trickled out, SDF and coalition officials screened them. Women and children were transferred to camps miles away. Men suspected of links to the militant group were taken into custody at other facilities.

Officials estimate there are hundreds of IS militants left in the small patch of territory in Baghouz, and that they will likely fight till the end.

Bali would not speculate on how long the military operation might take but said he expects a "fierce battle."

He said the battles are expected to take place in a very small area that includes a complex network of tunnels, as well as suicide bombers and land mines.

"The battle to finish off what is left Daesh has started," said SDF commander Adnan Afrin, using the Arabic acronym for IS.

The capture of the last pocket still held by IS fighters in Baghouz would mark the end of a devastating four-year global campaign to end the extremist group's hold on territory in Syria and Iraq — their so-called "caliphate" that at the height of the group's power in 2014 controlled nearly a third of both Iraq and Syria.

It would allow U.S. President Donald Trump to begin withdrawing the estimated 2,000 U.S. troops from Syria, as he declared in December he would do. Though last week he partially reversed course and agreed to keep a residual force of perhaps a few hundred troops as part of an international effort to stabilize northeastern Syria.

The resumption of military operations against IS breaks a dayslong standoff while the civilians were being evacuated. In the last week alone, 13,000 people, most of them women and children, arrived at the al-Hol camp in Hassakeh province which now houses approximately 45,000 people, according to the United Nations.

In a statement Friday, the U.N. cited reports that more than 84 people, two thirds of them young children under five years of age, have died since December on their way to al-Hol camp after fleeing the extremist group in Syria's Deir el-Zour province.

"Many of the arrivals are exhausted, hungry and sick," according to Jens Laerke, spokesman of the U.N. Office for the Coordination of Humanitarian Affairs (OCHA), at a news briefing in Geneva.