U.S.-backers forces fighting to take back the last Islamic State group outpost in Syria say they are facing difficulties defeating the group.

A spokesman says their effort is being slowed by mines, tunnels, and the possibility of harming women and children still in the village.

Dozens of men and women were seen walking around the besieged IS encampment in the village of Baghouz Sunday, as fighters from the Kurdish-led Syrian Democratic Forces watched from a hilltop close by.

SDF spokesman Kino Gabriel said the camp was approximately 250 km in size — much the same area it was five weeks ago, when the SDF said it was going to finally conclude the battle.

"We are facing several difficulties regarding the operations," Gabriel told reporters outside Baghouz Sunday.