The U.S.-backed Syrian Democratic Forces (SDF) expect a "fierce battle" with Islamic State militants who are still holed up in the group's last enclave in eastern Syria, Mustafa Bali, the head of the SDF media office, told Reuters on Friday.

U.S. President Donald Trump said on Thursday that the SDF had retaken 100 percent of the territory once held by Islamic State.

But Bali said Islamic State militants were still holed up in Baghouz, a village on the Iraqi border, and had not surrendered. "We won't storm the village and declare it liberated unless we have completely confirmed the departure of civilians."

"We expect a fierce battle".