US Secretary of State John Kerry on Saturday sought to muster European Union support for military strikes against Syria, after a G20 summit failed to resolve bitter international divisions on the issue.

US Secretary of State John Kerry on Saturday sought to muster European Union support for military strikes against Syria, after a G20 summit failed to resolve bitter international divisions on the issue.

Kerry went into informal talks with the EU's 28 foreign ministers in Lithuania with the bloc itself sharply split on Syria and most nations highly reticent over military action.

EU diplomats reported intense negotiations taking place to seek a consensus on Syria with France and Denmark supportive of a US-led strike but Germany, Sweden and others refusing to endorse action without a UN mandate or a debate within a UN framework.

The talks take place after US President Barack Obama and Russian leader Vladimir Putin failed to bridge their differences at the G20 summit of top global powers in Saint Petersburg.

The world is still waiting for a much-anticipated report by United Nations inspectors on the deadly August 21 attacks that left hundreds dead.

Later Saturday, Kerry is due to fly to Paris for talks with French officials. He will meet Arab League leaders there on Sunday to update them on Syria and on progress in the Zionist-Palestinian peace process.

He will travel on to London for talks late Sunday with Palestinian president Mahmoud Abbas, before flying home Monday.

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. He will lead the way with a five-hour vigil in St Peter's Square.