By Firas Dalati

DAMASCUS, Feb 18 (Reuters) - Fewer than 1,000 families remain in Syria's al-Hol camp, where relatives of suspected Islamic State militants are being held in the northeast of the country, after thousands fled last month when government forces seized control of the area from the Kurdish-led Syrian Democratic Forces, former camp director Jehan Hanna said on Wednesday.

Al-Hol camp, near the Iraqi border, is one of the main camps for detaining relatives of suspected Islamic State fighters who were captured during the US-backed campaign against the militant group in Syria.

Control of the camp changed hands last month when government forces led by President Ahmed al-Sharaa seized large areas of the northeast of the country from the Kurdish-led Syrian Democratic Forces, including several prisons where Islamic State fighters were being held.

The U.S. military said last week that it had completed the mission of transferring 5,700 adult Islamic State detainees to Iraq.

Jihan Hanna, who is still coordinating with international agencies and the Syrian government, told Reuters that the remaining families are Syrian nationals and are being transferred to a camp in Aleppo. She added that most of the foreigners in the camp have fled.

The Syrian government has not yet responded to requests for comment.

The latest data obtained by Reuters on the camp, dated January 19, the day before government forces took control of the camp, indicates that the number of families detained there is 6,639, comprising 23,407 people, mostly Syrians and Iraqis, in addition to 6,280 foreigners of more than 40 nationalities.

• "Disturbances and anxiety" in the camp

Meanwhile, the UN refugee agency said it had observed "a significant decrease in the population of al-Hol camp in the past few weeks," adding in a statement to Reuters that there were no confirmed figures on the number of those remaining.

The commission added that during the beginning of the week, "the camp administration advised the commission not to enter it because of the unrest and anxiety prevailing there."

The Syrian government accused the Syrian Democratic Forces of withdrawing from al-Hol on January 20 without any coordination.

The Syrian Democratic Forces said in a statement issued that day, "Our forces were forced to withdraw from the al-Hol camp and redeploy to the vicinity of northern Syrian cities that are exposed to increasing risks and threats."

A security source in the Syrian government said that most of the detainees in the camp escaped that day during a five-hour period when the guards were absent, adding that some of them left with men who came to take their relatives to unknown destinations.

The security source and a source from a non-governmental organization working there said that a section of the camp that housed the most dangerous detainees, known as the Annex, is now empty.

The security source said that the fugitives had spread throughout Syria and that the security authorities, in cooperation with international partners, had established a unit "to follow up on the matter and pursue those wanted."

Some of them left Syria.

A Lebanese security source said the army interrogated more than ten Lebanese who crossed the border illegally from Syria after leaving the al-Hol camp.

The Syrian government's Directorate of International Cooperation said on Tuesday that hundreds of people, mostly women and children, had been transferred from al-Hol camp to another camp that had recently been set up near the town of Akhtarin in northern Aleppo province.