Obama warns of Russian 'recipe for disaster' in Syria

US President Barack Obama warned on Friday that Russia's aggressive military campaign in Syria supporting strongman Bashar al-Assad is a "recipe for disaster," though Washington could still work with Moscow on reducing tensions.

Differences between the two have punctuated the last several days of the crisis, in which Russian jets have pounded Syrian opposition forces, but Obama stressed that "we're not going to make Syria into a proxy war between the United States and Russia."

Moscow carried out a fourth day of air strikes on Saturday in Syria, saying it targeted Islamic State (IS) militants, as Russian President Vladimir Putin faced increased international criticism over his military campaign.

The West has raised concerns that Russia is using its campaign against "terrorists" as a pretext to strike at moderate rebel groups opposed to Assad in a bid to bolster its ally.

Putin "doesn't distinguish between ISIL and a moderate Sunni opposition that wants to see Mr Assad go," Obama told reporters.

"From their perspective, they're all terrorists. And that's a recipe for disaster."

The Russian defence ministry and the Kremlin said its planes bombed IS targets six times on Friday and also hit the group's rival, Al-Qaeda's Syrian affiliate Al-Nusra Front.

Russian raids on rebels is 'only strengthening' IS

The American president said he had made it clear to Putin during their meeting in New York earlier this week that it's not possible to "rehabilitate" Assad in the eyes of Syrians.

"This is not a judgment I'm making," he added. "It is a judgment that the overwhelming majority of Syrians make."

Obama also noted that he would not join the Russian military campaign as Moscow acts in a way to support Assad rather than going after IS.

"The Russian policy is driving those folks (rebels) underground, or creating a situation in which they are de-capacitated, and it's only strengthening ISIL." he said.

Obama said the US wanted the trained Syrian fighters to focus on IS, while these forces were also bombed by the Syrian government. 

Just 5% of Russian airstrikes targeted IS

British Defence Secretary Michael Fallon, meanwhile, said that just five percent of Russian air strikes had targeted IS fighters.

"We're analysing where the strikes are going every morning," he said. "The vast majority are not against IS at all."

Russia was "shoring up Assad and perpetuating the suffering," Fallon added.

The US-led coalition urged Russia to stop attacking Syrian opposition forces, warning that it risked escalating the four-year civil war that has already killed up to 250,000 people.

"These military actions constitute a further escalation and will only fuel more extremism and radicalization," seven countries including Turkey, the United States and Saudi Arabia said in a statement.

"We call on the Russian Federation to immediately cease its attacks on the Syrian opposition and civilians."

Some of the rebel groups targeted by Russian jets have been supplied with training and weapons by the United States and its allies.

"I reminded President Putin that the strikes should be aimed at Daesh and only Daesh," French President Francois Hollande said after talks with his Russian counterpart in Paris, using the Arabic acronym for IS.

Several military sources and the Syrian Observatory for Human Rights monitoring group said Russia had hit areas controlled by groups other than IS.

A security source said they had been aimed at "military positions and command centers held by the Army of Conquest in Jisr al-Shughur... and Jabal al-Zawiya in Idlib".

'Residents very afraid'

In Raqa, activists and residents said IS cancelled Friday prayers and emptied mosques because they feared more Russian strikes.

"The residents are very afraid, especially if the Russians are going to operate like regime planes by targeting civilians," said activist Abu Mohammad, who is from Raqa.

Western nations including France say they are prepared to discuss a political solution with elements of the Syrian government but insist Assad must leave power.

Putin, on the other hand, says Assad should stay.

Alexei Pushkov, a Putin ally and senior lawmaker, said the campaign of Russian air strikes will last for three to four months and will increase in intensity.

He said more than 2,500 air strikes by the US-led coalition in Syria had failed to inflict significant damage on IS, but Russia's campaign would be more intensive.

Syria's Foreign Minister Walid Muallem said Damascus would take part in UN talks aimed at launching formal negotiations on ending the four-year war but will not be bound by their outcome.

'They ignore the killing of civilians'

Meanwhile, Turkish President Recep Tayyip Erdogan said Russian air attacks in Syria have killed moderate opposition forces as well as civilians but not IS militants.

"We learned that 65 people died during the ongoing Russian operations. Where? Around Hama, Homs and Aleppo. It is too significant. Because Russia expressed [to] our embassy in a written statement that it will struggle against Daesh here," Erdogan said.

“But, it [Russia] did not make this against Daesh; literally it made this against moderate opposition, which has been resisting the regime. Civilians were killed. They ignore the killing of civilians," he added in remarks made in a televised interview with Al-Jazeera late on Friday.

Erdogan said he will talk with Putin over the killings.

"Since we are two friendly countries, I will ask them to review their steps on this issue, because we have sorrow in the region and we bear the pain. Russia does not have a border with Syria, but I have a border of 911 kilometers [with Syria]," said Erdogan.

Turkey has welcomed Syrian refugees since the beginning of the civil war in March 2011 and is now hosting around two million people under temporary protection regulations.

Erdogan said: "We look after two million people. Russia does not. Why is Russia so interested in Syria? I want to understand this."

Fourth day

Meanwhile, the Russian defence ministry said on Saturday that its air strikes had destroyed an IS post near Raqa among other targets.

"Over the past 24 hours SU-34 and SU-24M jets of the Russian airborne formation in Syria made more than 20 sorties over nine Islamic State infrastructure facilities," the defence ministry said. 

SU-34 fighters jet dropped a concrete busting BETAB-500 bomb on a command post in the area of IS stronghold Raqa, releasing video of the strike.

SU-24 bombers also destroyed a warehouse that stored ammunition in the mountains near the city of Jisr al-Shughur in Idlib province in northwestern Syria.

Russian unmanned aerial vehicles continue to monitor the areas under control of IS, the statement said.

SU-34 fighter jets also targeted a training camp belonging to IS near the town of Maaret al-Numan in Idlib province and destroyed ammunition and equipment, the ministry said.