MARAWI CITY, Philippines (Reuters) - Four weeks since fierce fighting broke out in the southern Philippines, some people who fled the battle are dying in over-crowded and unsanitary evacuation centers, health officials say.

Children, who left their homes with their families to avoid the intense fighting between government forces and insurgents from the Maute group, eat their meals inside the evacuation centre in Baloi Village, Lanao Del Norte, Philippines June 19, 2017. REUTERS/Romeo Ranoco

At least 24 people have died in the centers since fighting between security forces and Islamist militants erupted in Marawi City, Health Secretary Paulyn Ubial told reporters.

Alinader Minalang, the health director for the Lanao del Sur province which includes Marawi, said 300 cases of diarrhoea had been recorded among the nearly 40,000 people huddled in emergency shelters set up in community halls, gymnasiums and Islamic schools.

Many of those who died were elderly and had pre-existing conditions, but at least two of the fatalities were due to diarrhoea.

“The cause of the increase in diarrhoea cases is sanitation issues and a lack of sources of potable water,” Minalang said.

In the centers, families of up to a dozen people sleep together on concrete floors, and in some places hundreds are sharing a single toilet.

“My children are getting sick. One has diarrhoea and another has an allergic reaction on his skin – the water we have to use here is not good,” said Tarhata Mostare, who was staying with more than 800 people in a high school hall in Iligan City, 40 km (25 miles) km from Marawi.

She walked out of Marawi City along with thousands of others just hours after delivering her fifth child, and trekked for hours with the infant swaddled in cloth and her own traditional malong, or long skirt, drenched in blood.

“We call him Martial Law,” she said, looking at her baby boy Sahir, his head now crowned with fine hair.

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On the date of Sahir’s birth, May 23, Philippine President Rodrigo Duterte declared martial law across the southern island of Mindanao, vowing to drive out the militants – an alliance of groups that have pledged allegiance to the Islamic State group.

The army says nearly 350 people have been killed in the fighting, including 257 militants, 62 soldiers and 26 civilians. Hundreds of people are unaccounted for, believed to be hiding in the basements of a city that has been pummeled by government air strikes. Residents have said they have seen 100 bodies in the debris of ruined homes in the battle zone.

WANT TO GO HOME

The mostly Muslim evacuees are eager to return home by the weekend for Eid al-Fitr, the biggest festival of the year that marks the end of the holy month of Ramadan. But for many, their homes have been devastated by weeks of artillery fire and aerial bombardment.

The army says it is nearing victory, but hostilities will have to be followed by a lengthy cleanup operation – unearthing and disarming unexploded ordnance, and scouring for possible booby traps – before residents can go home.

“I will be the happiest woman in the world if I am allowed to return,” said Salema Ampasong, 28, who was among about 1,000 evacuees given shelter in a gymnasium in the town of Balo-i, several miles outside Marawi.

A fruit vendor, she said she had lost all her possessions, “but I would still want to come home”.

In Balo-i, there’s just one working toilet for the center’s 1,025 residents. On the wall a poster produced by the Philippine Red Cross instructs evacuees how to wash their hands. There are no basins with taps, and evacuees wash - and even defecate - in a nearby river.

Malnutrition is another worry in the centers.

Melia Sarap, the provincial nutritionist for Lanau del Sur, said initial surveys of more than 600 evacuees had found six cases of severe malnutrition and 20 cases of moderate malnutrition.

“The evacuation centers are very congested and the infection you can catch could result in malnutrition,” Sarap said. “If we just depend on rations alone (the malnutrition rate) can rise up.”

Particularly of concern were lactating mothers, she said, for whom a nutritious diet is vital for both the mother’s health and the development of the child.

“It’s not good to feed children just on canned goods like this,” said Tarhata, breastfeeding her baby. “But it’s the only way we can survive.”