BAGHOUZ, Syria - The Islamic State group extremists were defending the last pocket of their "caliphate" in Syria on Monday, as EU foreign ministers meet to discuss the crisis after US President Donald Trump called on European nations to take back their foreign fighters.

Diehard IS militants are trapped in their last patch of territory of less than half a square kilometer in eastern Syria near the Iraqi border.

They have prevented civilians from fleeing by blocking roads out of the village of Baghouz, the US-backed Syrian Democratic Forces fighting them said on Sunday.

On a rooftop on the edges of the village, an SDF fighter said that the frequencies used by the extremists to communicate had gone dead.

"Now their area of control is really squeezed and they don't have as many walkie talkies. They're not talking to each other as much," he added.

SDF spokesman Mustefa Bali said the IS group had blocked roads out of its holdout, preventing up to 2,000 civilians from escaping.

Civilians who have been able to escape reported that IS militants were using women and children "as human shields", said Sean Ryan, a spokesman for the US-led coalition.

Thousands of people have streamed out of the so-called "Baghouz pocket" in recent weeks, but at a collection point for new arrivals on Sunday, dozens of tents and a few trucks sat empty.

On Monday, EU foreign ministers were scheduled to meet in Brussels to discuss the war-torn country, after appeals for a "European solution" to the hundreds of foreigners - including from the United Kingdom, France, Germany, Ireland, Canada and Italy - who have been arrested by the SDF for allegedly fighting with the IS group.

The Kurdish-led group has repeatedly called on European governments to take back their citizens.

The issue has taken on greater urgency, however, amid fears of a security vacuum since Trump's shock announcement in December that US troops would withdraw.

"The United States is asking Britain, France, Germany and other European allies to take back over 800 ISIS fighters that we captured in Syria and put them on trial," Trump said in a tweet.

Otherwise, "we will be forced to release them. The US does not want to watch as these IS fighters permeate Europe, which is where they are expected to go."

Meanwhile, US Special Representative for Syria Engagement James Franklin Jeffrey said on Sunday that the US will not make an abrupt and rapid withdrawal of its troops from Syria and will consult closely with its allies on the issue.

"We've been telling them (allies) continuously this is not going to be an abrupt, rapid withdrawal but a step-by-step withdrawal," he said.

AFP - Reuters