Iraq crisis: UN concern over Ramadis displaced by IS advance
The UN says it is trying to reach some 40,000 civilians displaced from Ramadi by the advance of Islamic State (IS).
The largest concentration is at Bzebiz bridge which has been closed by the authorities to prevent those fleeing from entering Iraq's capital, Baghdad.
There are reports of children dying of dehydration in the heat, the UN's Dominik Bartsch told the BBC.
IS seized Ramadi earlier this week. Pro-government militias are preparing an offensive to retake the city.
IS militants are reported to be pressing eastwards from Ramadi - capital of Anbar province - down the Euphrates Valley towards Habbaniya where the Shia militias have been deployed.
If they take Habbaniya, the Sunni militants will be close to linking up directly with Falluja, a city close to Baghdad which they have held for more than over a year despite repeated attacks by government forces.
It is unclear why the Bzebiz bridge over the Euphrates was closed, though there have been concerns that militants could mingle with the displaced and infiltrate the capital.
Bzebiz is seen as the one safe crossing to Baghdad from Anbar province.
Mr Bartsch, the UN Deputy Humanitarian Co-ordinator for Iraq, told the BBC there were three main locations of internally displaced people from Ramadi, with the most serious across the river at Bzebiz bridge.
There was serious concern about women, children, the elderly and those sick among the thousands stranded in the heat, he said.
The UN, he added, was trying to send food and hygiene parcels to them.
Mr Bartsch said the UN was also trying to establish how many people were displaced around Habbaniya - staging post for the counter-offensive - to make sure people were not stranded in the middle of warring parties.
Very little information is available about those still in Ramadi, he said.
"We hear stories of reprisals, of shootings, of individual persecution of civilians who have remained in the city."
The hospital there had been badly damaged and ceased to function.
In addition to Ramadi, this week IS militants have also seized the last Syrian government-controlled border crossing between Syria and Iraq on Friday and, in Syria, the ancient city of Palmyra.
Some observers said they now controlled 50% of the Syria's entire territory - as well as a third of Iraq.
On Friday, Iraqi Deputy Prime Minister Saleh al-Mutlaq warned that fighting IS was no longer a "local matter", and called on the international community to act.
An international coalition has been carrying out air strikes against the militants in Iraq and Syria for months.
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