PARIS — The United States said on Sunday it did not rule out returning to the U.N. Security Council to secure a Syria resolution once U.N. inspectors complete a report on a chemical weapons attack, but indicated Arab countries were seeking a tough response.

Speaking at a news conference in Paris after meeting key Arab foreign ministers, Secretary of State John Kerry said they were leaning towards supporting a G20 statement — already signed by 12 countries — that called for a strong international response following an Aug. 21 chemical attack in Syria.

Washington and Paris say forces loyal to President Bashar al-Assad were behind the attack in which more than 1,400 are estimated to have been killed, and that he should be deterred from using such weapons again.

French President Francois Hollande, increasingly under pressure at home and among European partners to seek a U.N. mandate before any military intervention in Syria, on Saturday suggested he could seek a resolution at the U.N. Security Council despite previous Russian and Chinese vetos.

"On President Hollande's comments with respect to the U.N., the president (Obama), and all of us, are listening carefully to all of our friends," Kerry said. "No decision has been made by the president."

The meeting with Arab ministers, including from Saudi Arabia, Egypt, Qatar and the United Arab Emirates, followed talks in Lithuania with European foreign ministers, who blamed the attack in Syria on Assad but refused to endorse military action.

"All of us agreed - not one dissenter - that Assad's deplorable use of chemical weapons, which we know killed hundreds of innocent people . . . this crosses an international, global red line," Kerry said alongside his Qatari counterpart Khaled al-Attiya.