(AFP) AMMAN, Jordan — United Nations agencies have expressed “deep concern” for the safety and security of nearly 50,000 Syrians stranded in the desert near their war-wracked country’s southern border with Jordan.

A statement issued on Sunday in Amman said an estimated 4,000 people at Hadalat and 45,000 mostly women and children at Rukban were stuck on the frontier.

A suicide bombing claimed by the Islamic State jihadist group in June last year killed seven Jordanian soldiers in no-man’s land near the Rukban border crossing.

Soon afterwards, the army declared Jordan’s desert regions that stretch northeast to Syria and east to Iraq “closed military zones.”

Jordan is part of the US-led coalition fighting IS.

“Airstrikes have been reported in the area in the last few days, causing serious distress and panic among the population fearing for their lives with the heightened risk of escalated hostilities,” Sunday’s statement said.

It said that although no casualties have yet been reported among the stranded Syrians, “the area is increasingly unsafe,” prompting some people to leave the area.

This exposed them to “further danger and deprivation in an inhospitable desert location, unsure of where to go in search of safety.”

The UN said the most vulnerable, mostly women and children, were unable to return home because of the war in Syria.

More than 330,000 people have been killed in Syria and millions displaced since the country’s conflict erupted in March 2011 with anti-government protests.

Jordan shares a desert border of more than 370 kilometers (230 miles) with Syria.

The UN refugee agency says it has registered more than 650,000 Syrian refugees in Jordan since the conflict began. Amman says it is hosting 1.3 million Syrian refugees.