GENEVA/DAMASCUS  - The United Nations appealed for $6.5 billion for Syria and its neighbours on Monday to help 16 million people next year, many of them hungry or homeless victims of a 33-month-old conflict that has no end in sight.

The Syrian appeal accounted for half of an overall funding plan of $12.9 billion to help 52 million people in 17 countries, announced on Monday by UN emergency relief coordinator Valerie Amos at a meeting of donor countries in Geneva.

“This is the largest amount we have ever had to request at the start of the year,” she told a news conference, referring to the worldwide appeal. She said the money requested for Syria was the largest UN appeal ever for a single crisis.

“The increasing number of internally displaced people and refugees is generating greater needs across all sectors and straining the capacities of neighbouring countries, with profound regional consequences,” the appeal said of Syria.The United Nations sent its first delivery of humanitarian aid by air to Syria from Iraq on Sunday and said it plans to deliver more food and winter supplies to the mainly Kurdish northeast in the next 12 days. It is seeking $2.3 billion to help 9.3 million people in Syria next year, compared with its 2013 appeal of $1.4 billion, of which only 62 percent has been received, UN figures show.

For five neighbouring countries - Egypt, Iraq, Jordan, Lebanon and Turkey - the world body is seeking $4.2 billion to assist up to 4.1 million Syrian refugees and host communities who will be given food aid including cash or vouchers.

UN agencies aim to provide food, clean drinking water, shelter, education, health services and polio vaccines to Syrians inside and outside the devastated country.

The UN World Food Programme aims to feed 4.25 million people in Syria, where it reached only 3.4 million in November. “This is the worst humanitarian crisis that we have seen in decades, with every day more vulnerable Syrians pushed into hunger,” Muhannad Hadi, WFP’s Syria Emergency Coordinator, said. The overall UN appeal also includes aid to Sudan, South Sudan, Yemen, Democratic Republic of Congo, Afghanistan and the Philippines.

Meanwhile, the Syrian air force was on Monday accused of killing 76 people by unleashing barrels packed with explosives on Aleppo, a focal point for fighting between regime and rebel forces.

The number of people slain in Sunday’s bombing of Aleppo “with explosive-packed barrels... rose to 76,” including “28 children and four women,” said the Syrian Observatory for Human Rights, updating its previous toll of 36 dead.

Observatory director Rami Abdel Rahman said it was “one of the heaviest tolls from air raids since the beginning of the war” that flared after a brutal regime crackdown on Arab Spring-inspired democracy protests that erupted in March 2011.

Explosive-laden barrels were dropped on six rebel-controlled districts in the east, including Sakhur, Ard al-Hamra and Haydariyeh, Abdel Rahman said.

The Observatory and activists said government forces frequently drop the barrels filled with TNT on rebel-held areas of the war-torn country from helicopters and warplanes. “The barrels of explosives are not like bombs. Their impact is not accurate as they are dropped without any guidance system, and that is why they cause a large number of victims,” said Abdel Rahman.

The devices are made up of metal barrels that have a layer of concrete inside them “so that they cause as much destruction and death as possible,” according to Abdel Rahman.

There are two types of barrel bombs, one of which is home-made, and the other of which is made in factories. A Syrian security official said the army prefers the TNT-packed barrels because they are cheaper than regular bombs, which need to be imported from Russia.

The Aleppo Media Centre, a network of activists on the ground, called Sunday’s raids on the northern city “unprecedented”.

“Everyone is looking up at the skies and watching the planes. But there’s nothing to be done,” AMC activist Mohammed al-Khatieb said.

Aleppo, Syria’s second city and pre-war commercial hub, is now divided between areas occupied by troops loyal to President Bashar al-Assad and rebel fighters.

Fighting that erupted with a rebel offensive in July last year has caused massive damage to the historic city. Activists posted video footage online of the aftermath of Sunday’s barrel bomb attacks, showing bulldozers clearing rubble from the streets as men searched for survivors in wrecked buildings.

The barrel bombings came as Swedish expert Ake Sellstrom prepared to brief the United Nations Security Council on the use of internationally-banned chemical weapons in the unrelenting war.

Sellstrom led an investigation into the alleged use of chemical weapons in Syria.