Thousands of civilians have fled Iraq's Tal Afar since an offensive against the jihadist stronghold was launched two days ago, but thousands more remain stuck in the city, the United Nations said Tuesday.

The International Organization for Migration (IOM) said its teams were "responding to thousands of civilians fleeing Tal Afar since the launch of the military campaign to retake the city".

The assault on the last major bastion of the Islamic State group in northern Iraq was launched at dawn Sunday, only weeks after Iraqi forces seized the country's second city Mosul from the jihadists.

Since Friday, more than 3,000 people have arrived at two emergency sites run by IOM, many turning up with just the clothes on their back, the UN agency said in a statement.

The UN refugee agency (UNHCR) said it had received around 1,500 families, or some 9,000 people, from Tel Afar at the Hamman Al Alil transit centre in the past week.

And it said it was preparing to accommodate nearly 30,000 more people displaced from the city in the coming days.

Tel Afar was once home to around 200,000 people, but it remains unclear how many civilians remain inside the ravaged city, with humanitarian actors unable to gain access since it was seized by IS in 2014.

- Human shields? -

UNHCR said it estimated that thousands of people could still be in the city, warning that civilians are likely to be held as "human shields again" by IS fighters, as was the case in Mosul.

Conditions inside the city are believed to be "very difficult," UNHCR said in a statement, pointing to diminishing food, water and health facilities and a lack of electricity.

"People are said to have been surviving on unclean water and bread for the past three to four months," it said.

Families who flee also face huge risks, with many reporting seeing dead bodies along the way, some believed to have been killed by extremist groups and others likely dying from dehydration or illnesses, UNHCR said.

Many are forced to walk long distances to reach safety "without food or water, at times for up to 20 hours and in scorching heat," the agency said, in an area where temperatures can reach 50 degrees Celsius (122 degrees Fahrenheit).

UNHCR said many children, elderly and other vulnerable people are being left behind in Tal Afar since they are unable to make the arduous journey.

Among those who do make it to safety, many suffer from dehydration and large numbers are suffering wounds from sniper fire and exploding mines, it said.

Source: AFP