As Muslims around the world mark the Eid al-Adha holiday, sharing festive meals, children trapped in besieged areas around the Syrian capital are going hungry, activists and medics say.

In some areas children have died from severe malnutrition, according to one NGO, and a cleric told AFP he had issued a religious ruling allowing the eating of dog and cat meat.

For Muslims, Eid is a time for children to receive new clothes and play with friends after sharing a festive meal with their families.

But in a string of rebel-held areas under a months-long army siege south and east of Damascus, activists say food has all but run out and doctors lack the means to treat their patients.

"Of course there is no Eid for the children here" in Moadamiyet al-Sham, a suburb southwest of Damascus, said activist Abu Malek.

"For them, Eid will come when they see a plate of rice and bulgur," he added, speaking to AFP via the Internet.

Residents of Moadamiyet al-Sham are surviving on herbs and vegetables they have planted.

"We no longer have any food in the stockpiles. Everyone is planting in the orchards and the streets," said activist Abu Hadi, adding that no bread had entered the area for months.

But harvesting the food is dangerous, "and people have died in the orchards because of the shelling", he said.

Rami Abdel Rahman, director of the Syrian Observatory for Human Rights, said many children in Moadamiyet al-Sham were malnourished.

"Children are worst off because they need the right kinds of food in order to grow. Adults can survive on whatever they can find, but what about the children?"

The army says "terrorists," its term for the rebels, have trapped civilians against their will.

But activists accuse the military of using the siege to try to turn people against the rebels.

"It is a war crime to besiege civilians," Abdel Rahman said.

Shocking amateur videos have been distributed by activists from the town, showing visibly malnourished children.

One video shows a boy identified as Ibrahim Khalil laid out on a stretcher. His ribs and cheekbones protrude from underneath his pale skin, and dark circles surround his eyes.

Another video shows a girl with her two baby siblings, appealing for help so her family can secure baby milk.

"There is no road... The road is closed... What are we going to do?... We are feeding them milk but it's expired," says the little girl, as the babies cry.

For some, relief came earlier this week, when the International Committee of the Red Cross and the Syrian Red Crescent evacuated 3,500 people from Moadimayet al-Sham with the agreement of the authorities.

But only children, women and old men were able to leave, with the wounded left behind and aid workers prevented from entering the area.

"There are many more, including children, who remain in the town," said Magne Barth, head of the ICRC delegation in Syria.

The situation is just as bad for children in other rebel-held areas near Damascus.

"On any given day in the emergency room, some four out of 10 patients I see are malnourished children," said Abu Mohammad, a doctor working in a field clinic in the Marj area east of the capital.

"Many children have very low blood pressure, fatigue, dizziness, and a reduced (disease-fighting) white blood cell count. The worst affected by the food shortages are children aged under two years," he added.

The hardest part is not having the right medical equipment or food to fight malnutrition, he told AFP.

"I get depressed in the clinic, because we don't have what we need to fight this."

Also affected is Yarmuk, a Palestinian refugee camp in southern Damascus that has turned into a battleground in recent months.

"Nothing, not even bread or flour has been allowed in for 96 days," according to Palestinian-Syrian activist Ali Abu Khaled, who said he is "lucky to get one small meal a day."

Speaking to AFP on the eve of Eid, a cleric in southern Damascus said a man in his area recently ate dog meat out of desperation.

"We issued a religious edict allowing people to eat dog and cat meat. Not because it is religiously permitted, but because it is a reflection of the reality we are suffering," said Sheikh Saleh al-Khatib, who has been on hunger strike for nine days.

"People here have nothing for their children. I am on strike because I want to help save food for others."