KUWAIT CITY (AP) — The UN chief made a dramatic appeal Wednesday for a major boost in relief aid for Syria, calling for an end to the fighting “in the name of humanity” as an international conference opened in Kuwait with both foes and backers of President Bashar Assad.

The UN appeals for up to $1.5 billion reflects the deepening civilian crisis for an estimated 700,000 refugees who have fled Syria and more than 2 million others uprooted or suffering inside the country as the civil war widens — including what peace envoy Lakhard Brahimi called “unprecedented levels of horror” in an address to the Security Council after at least 65 bodies were found in a suspected execution-style killing near Aleppo.

Ban urged all sides “and particularly the Syrian government” to halt attacks in the 22-month-old civil war that the UN says has claimed more than 60,000 lives.

“In the name of humanity, stop the killing, stop the violence,” Ban told envoys from nearly 60 nations, including Russia and Iran, key allies of Assad’s regime.

Before the latest donors’ conference, Ban described the international humanitarian response to Syria as “very much limited” in comments to the official Kuwaiti News Agency.

But the meeting appeared to leverage more pledges. Kuwait’s ruler, Sheik Sabah Al Ahmad Al Sabah, promised $300 million in a move that could prompt other donations from Gulf Arab allies, which are major backers of Syrian rebel factions. On Tuesday, the European Union and the US promised a total of nearly $400 million.

While international aid channels are open to refugee camps in places such Turkey and Jordan, there is far more limited capacity to organize relief efforts inside Syria because of the fighting and controls by Assad’s regimes.

Paris-based Medecins Sans Frontieres said the U.N. and others need to open more routes for aid to reach rebel-held areas, which now receive only a “tiny share” of international humanitarian help.

“The current aid system is unable to address the worsening living conditions facing people who live inside Syria,” said a statement by the group’s president, Marie-Pierre Allie.

The escalating hardships in camps outside Syria also can be used by Assad’s government as potential fodder in its claims that rebels are responsible for the country’s collapse, said Fawaz Gerges, head of the Middle East Center at the London School of Economics.

“The misery of the refugees, their suffering in neighboring countries, provide the ammunition for Assad, who is saying to them, ‘See, you have no one else but your country, so come home,'” he said.

Copyright 2013 The Associated Press.