VILNIUS: European Union nations called for a "strong" response on Syria Saturday but stopped short of endorsing military action, as US President Barack Obama warned of the dangers of turning "a blind eye" to chemical attacks.
Fresh from a G20 summit in Saint Petersburg where he failed to win over world leaders to his cause, Obama urged Congress to authorise an intervention over President Bashar al-Assad's alleged use of chemical weapons.
"We cannot turn a blind eye to images like the ones we've seen out of Syria," Obama said in his weekly address.
"That's why I call on members of Congress, from both parties, to come together and stand up for the kind of world we want to live in."
Congress reconvenes on Monday and Obama is set to address the nation Tuesday about a possible US response to the August 21 attack that left hundreds dead on the outskirts of Damascus.
Washington meanwhile sought to muster support from its divided allies in Europe, with US Secretary of State John Kerry holding protracted talks with the EU's 28 foreign ministers in the Lithuanian capital before leaving for France, after which he will visit Britain.
Split between Paris and London, who are hardline supporters of US-led military action, and smaller nations reluctant to act without a UN mandate and fearful of "day-after" consequences of an attack, the EU ministers managed to hammer out a compromise in Vilnius.
A statement read out by EU foreign policy chief Catherine Ashton dubbed last month's suspected chemical weapons attack "a war crime and a crime against humanity".
There was "strong evidence that the Syrian regime is responsible," the statement said, echoing earlier claims made by Washington, London and Paris but strongly rejected by key Syria ally Moscow.
"The international community cannot remain idle," the statement added. "A clear and strong response is critical to make clear that such crimes are unacceptable and that there can be no impunity."
On heading to Paris, Kerry welcomed the "strong statement about the need for accountability... that support the efforts to hold the Assad regime accountable for what he's done."
In Riyadh, the Gulf Cooperation Council urged the international community to intervene immediately to "rescue" the Syrian people from "oppression."
Meanwhile, Catholics worldwide held a day of fasting and prayer for peace in Syria joined by Jews, Muslims and Orthodox Christians, with Pope Francis set to host a mass vigil.
The Vatican has warned military strikes could escalate the conflict and cause it to spill over into the region.
"Peace is a good which overcomes every barrier, because it belongs all of humanity #prayforpeace," Pope Francis wrote in one tweet, with another saying simply: "Never again war! War never again!"
Faced with a war-weary US public and little international support, Obama is bracing for an uphill battle to convince American lawmakers to back military action against Assad's regime.
According to a Washington Post survey, 224 of the current 433 House members were either "no" or "leaning no" on military action as of Friday. A large number, 184, were undecided, with just 25 backing a strike.
The Senate and the House are expected to vote on the issue within the next two weeks.
In France, the sole EU nation determined to join a US-led strike, the latest public opinion poll showed 68 percent of people opposed to military action, an increase of nine percentage points since late August.
The EU statement said there could be no end to the Syrian war without a political solution and urged the UN Security Council "to fulfill its responsibilities", a reference to Russia and China's refusal to sanction Assad.
Ashton meanwhile said the EU welcomed French President Francois Hollande's decision to await the release of a UN investigation into the August attack before taking action against Syria.
But Kerry made clear that Washington had not decided to postpone a decision on military action until the release of the UN report, though several EU ministers said he had pledged to make their case to Obama.
German Foreign Minister Guido Westerwelle urged the UN to publish its chemical weapons report "as quickly as possible".
Germany also announced it has signed on to a global statement, separate from the EU one, calling for "a strong response" to the alleged chemical weapons attack.
That made Germany the fifth EU member to back the statement issued at a G20 summit in Saint Petersburg on Friday and signed by 11 other countries -- including the US, Britain, France, Italy and Spain.
Russian President Vladimir Putin has warned that any intervention in Syria without the UN's blessing would be "outside the law".
Washington meanwhile is evacuating non-essential embassy staff from Beirut and urging Americans to avoid all travel to Lebanon and southern Turkey.