Approximately 1,000 Iraqi families have fled the advance of Islamic State militants and crossed the border to the Syrian province of Hassakeh, according to the Syrian government.

The United Nations High Commissioner for Refugees (UNHCR) agency estimated that the number of people fleeing Iraq and crossing the border into Syria was between 10,000 and 15,000 people.

"Nearly 1,000 Iraqi families who fled the Sinjar mountains because of the terrorism of the Islamic State have been welcomed in schools in Al-Maliki in Hassakeh province," Syria's social affairs minister Kinda Shamat said.

"We are committed to providing humanitarian aid to all the Syrian and Iraqi families affected by attacks by armed terrorist groups," Shamat added.

The move comes despite Syria being ravaged by a four-year civil war between the government forces of Syrian President Bashar al-Assad and Sunni Muslim rebels. More than 170,000 people have been killed in the fighting.

Up to 50,000 Yazidi Kurds were originally trapped in the Sinjar mountains following the Islamic State's siege on the town of Sinjar. Now many who have fled Iraq are finding safe havens in camps within Syria and other Yazidi communities.

"Most are staying in the Newroz camp near Al-Qamishli [in Hassakeh province], run by local NGOs. Other refugees are scattered among various Yazidi villages in Qahtania or urban areas," UNHCR spokesman Adrian Edwards said in a statement.

"Hundreds are sleeping in the open and more shelter and food aid is needed urgently," he added.

The surge of refugees across the border comes despite US airstrikes on Islamic State positions and humanitarian aid drops conducted by both the United Kingdom and the US.

An estimated 700,000 Yazidis have been displaced in the unrest and the United Nations has said that a few thousand still require "life-saving assistance" from dehydration and starvation in the arid mountains.