BRUSSELS (Reuters) - The European Union’s aid chief called for more humanitarian access in Syria on Tuesday at an international conference meant to support the country’s ailing peace prospects, but one that quickly got overshadowed by a chemical attack inside Syria.

European Union foreign policy chief Federica Mogherini takes part in a joint news conference during an international conference on the future of Syria and the region, in Brussels, Belgium, April 5, 2017. REUTERS/Yves Herman

As Christos Stylianides spoke at the gathering in Brussels, a suspected gas attack hit the rebel-held Idlib province, killing at least 58 people, including children.

The United Nations’ Syria envoy said the ‘horrific’ attack came from the air and that the U.N. Security Council would meet to demand accountability.

The EU’s top diplomat Federica Mogherini said Syrian President Bashar al-Assad held “primary responsibility”.

“Chemical weapons are the worst of war crimes,” she said.

The Brussels conference comes as Syria’s civil war enters its seventh year, raging on in large part due to the inability of regional and global powers to agree on how to end it.

“Humanitarian access is at a new low due to continued deliberate obstruction by all parties to the conflict,” Stylianides told the two-day conference.

“You remember east Aleppo, where no aid could enter for months despite our collective calls,” he said, referring to the government siege of rebel-held areas last year. “More Aleppos are everywhere in Syria.”

The United Nations has appealed for $8 billion this year to deal with one of the world’s worst humanitarian crises, with millions of people displaced inside Syria and in neighboring countries.

Qatar and Kuwait joined the EU, Norway and the United Nations to organize the latest international effort following conferences in Berlin, London and Helsinki to raise funds.

The European Union has already pledged 1.2 billion euros ($1.28 billion) for 2017. Other governments will come under pressure to make good on promises made in February 2016 at the London conference, which raised $11 billion over four years.

EU LACKS HARD LEVERAGE

Speaking on the sidelines of the conference, Nancy Wilson, the head of Relief International, said problems getting access and providing supplies were chief obstacles on the ground.

“You can’t run a health clinic if you don’t have clean water and medical supplies,” she said. “Some kind of political solution that would cease the fighting would be the biggest challenge.”

The EU called the conference to show support for the peace process by bringing together prime ministers, foreign ministers and ambassadors from some 70 countries.

But the bloc’s role in international attempts at bringing the war to an end has been largely marginal, as highlighted again by the absence in Brussels of top-level officials from Russia, Turkey and the United States.

Five million Syrians have fled into Turkey, Lebanon, Jordan, Iraq and the European Union to escape the conflict among rebels, Islamist militants, government troops and foreign backers.

The future of Assad, backed by Russia and Iran, remains the key point of contention, blocking political talks.

The EU says it will not pay for any post-war reconstruction unless there is a “credible political transition” that would give the opposition, moderate rebels and the various ethnic and religious groups a say in Syria.

“We caution against paying for Assad’s destruction without a political end to the war,” said European lawmaker Mariejte Schaake of the Netherlands.

The initial U.S. and Russian backing for the U.N.-led process has waned as Moscow now sponsors separate talks with regional powers Iran and Turkey.

Washington is now also at odds with Europe - while they used to agree that Assad must go, President Donald Trump has made fighting terrorism his top priority instead.