President Barack Obama met on Friday with his national security team to discuss the fight against Islamic State and the war in Syria, the White House said.

Reuters had reported that in the meeting Obama and his advisers would consider military and other options in Syria as Syrian and Russian aircraft continue to pummel the city of Aleppo and other targets, US officials said.

US officials said they considered it unlikely that Obama would order US air strikes on Syrian government targets, and they stressed that he might not make any decisions at the National Security Council meeting.

A readout of the meeting released by the White House noted that the United States had broken off bilateral talks with Russia on reaching a ceasefire in Syria. It said Obama directed his team to continue multilateral talks with "key nations" to seek a diplomatic resolution to the civil war.

The brief summary made no mention of other US options in Syria.

US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov will return to Syria talks on Saturday, three weeks after the failure of their painstakingly drafted ceasefire.

Kerry has pointedly avoided new bilateral negotiations with Lavrov, and his invitation to the Turkish, Saudi, Qatari and Iranian foreign ministers to join them for talks in Lausanne, Switzerland, will broaden the discussion to include the most powerful backers of Syria's government and rebels.

Pressure is rising for a halt to a ferocious, three-week-old Syrian government offensive to capture the rebel-held eastern zone of Aleppo, where the United Nations says 275,000 civilians still live and 8,000 rebels are holding out against Syrian, Russian and Iranian-backed forces.