US not against Russian strikes: Kerry

The United States does not oppose Russian air strikes in Syria if they target the Islamic State group, but Bashar Al Assad must step down, Secretary of State John Kerry said on Wednesday.

Kerry was addressing the United Nations Security Council hours after Russian jets hit targets in Syria, apparently in support of Assad's battle against rebel groups threatening his hold on power.

"If Russia's recent actions and those now ongoing reflect a genuine commitment to defeat that organization then we are prepared to welcome those efforts," Kerry said.

US forces, he added, are ready to "de-conflict" with Russian forces -- communicate to avoid accidental encounters on the battlefield -- "thereby increasing the military pressure on ISIL."

"But we must not and will not be confused in our fight against ISIL with support for Assad," he insisted.

"Moreover we have also made clear that we would also have grave concerns should Russia strike areas where ISIL and Al-Qaeda affiliated targets are not operating," he said.

"Strikes of that kind would question Russia's real intentions in fighting ISIL or protecting the Assad regime," he warned.

Early reports of Russia's strikes on Wednesday suggested they hit areas where other opposition groups, seen by the United States and its allies as moderates, have been fighting Assad's forces.

"We have informed Russia that we are prepared to hold these de-confliction talks as early as possible: this week," Kerry said.

"But let me be clear, the United States and the coalition will continue our ongoing air operations as we have from the very beginning," he said, referring to the year-old US-led campaign.

"We have conducted a number of strikes against ISIL targets in Syria over the past 24 hours including just an hour ago, and these strikes will continue."