US Secretary of State John Kerry is seeking to rally EU support for military strikes against Syria after a G20 summit failed to resolve bitter divisions between Washington and Moscow.
Kerry was in Lithuania on Saturday to press the case for punitive action against Syria after what the US says was a chemical weapons attack by the regime of President Bashar al-Assad near Damascus.
The EU's foreign policy chief Catherine Ashton said that the EU's 28 nations agreed that available information seemed to show strong evidence that the Syrian government carried out a chemical attack on civilians in August.
"[The government] is the only one that possesses chemical weapons agents and the means of their delivery in a sufficient quantity," Ashton told reporters after meeting EU foreign ministers in the Lithuanian capital of Vilnius.
The ministers agreed, she said, that the world "cannot remain idle" and said a clear and strong response was needed to prevent any future use of chemical weapons in Syria.
Kerry welcomed Ashton's comments.
"We are very grateful for the statement that came out of the meeting today with respect to Syria - a strong statement about the need for accountability," Kerry said after meeting EU foreign ministers in Vilnius, capital of Lithuanian, which currently holds the EU's rotating chair.
The EU is sharply split on the issue of military intervention, and Ashton said ministers stopped short of lending support to military action.
Only France has said it is ready to take part in military action, while Britain, whose parliament voted against any involvement, and Denmark have expressed support.
France was one of four European nations, with Britain, Italy and Spain, that signed a statement on Friday at the G20 meeting in St Petersburg calling for a "strong international response" to the chemical attack.
The statement, signed by 11 of the G20 nations, but not by Germany, said the response would "send a clear message that this kind of atrocity can never be repeated".
It did not specify military action and European diplomats said the language remained unclear.
US President Barack Obama and Russian leader Vladimir Putin failed to resolve their differences at the summit.
Obama said on Friday that the world could not "stand idly by" but Putin warned that it would be "outside the law" to attack without the UN's blessing.
Putin also said Russia would "help Syria" if the US were to strike, pointing to existing military, economic and humanitarian cooperation.
As well as the stubborn international differences, the US administration still has to win backing from Congress for any action against Syria.
The world is still waiting for a much-anticipated report by United Nations inspectors on the deadly August 21 attacks that left hundreds dead.
At the Russian summit, French President Francois Hollande vowed to wait for the UN report before joining any military action, a decision welcomed by Germany.
German Foreign Minister Guido Westerwelle urged the UN to publish its report "as quickly as possible" to help Europe's divided leaders determine a response.
Sweden's Foreign Minister Carl Bildt told reporters it was essential to wait for the UN report as "it will be the best picture we can get from any source".
"The Indians, the Brazilians, the Chinese and others don't really think that information from US intelligence is enough, and that's the world we live in," he said.
Russia and China, both veto-wielding permanent members of the UN Security Council, have on three occasions voted down resolutions that would have put pressure on Assad.
Later on Saturday, Kerry is due to fly to Paris for talks with French officials.
He will also meet Arab League leaders to update them on Syria and on progress in the Israeli-Palestinian peace process.
Pope Francis has appealed for a peaceful solution to the crisis, calling on the world to unite on Saturday in a day of fasting and prayer for Syria.