Russia carried out a third day of air strikes in Syria on Friday and said it had targeted Islamic State jihadists as President Vladimir Putin faced growing international criticism over his military campaign.
The Russian defence ministry and the Kremlin said its planes bombed IS targets six times on Friday and also hit the group's jihadist rival, Al-Qaeda's Syrian affiliate Al-Nusra Front.
But the West is concerned that Russia is also attacking rebel groups opposed to Syrian President Bashar al-Assad in a bid to bolster its long-term ally.
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 radicalisation," seven countries including the United States, Turkey and Saudi Arabia said in a statement.
"We call on the Russian Federation to immediately cease its attacks on the Syrian opposition and civilians," it added.
- IS stronghold 'hit' -
Russia said earlier it had hit the IS bastion of Raqa for the first time in raids on Thursday, destroying a "terrorist training camp" and a command post.
Islamic State is one of many groups fighting Assad and has seized control of large parts of eastern Syria and northern Iraq.
Washington and its allies accuse Moscow of using what it insists is a campaign against "terrorists" as a pretext to bomb other more moderate groups that oppose Assad.
Some of the groups targeted 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 Islamic State.
The Russian defence ministry said the strikes Friday had completely destroyed an IS facility used to produce explosive devices near the city of Maaret al-Numan in Idlib province in northwest Syria as well as a nearby base.
They also targeted the central Hama province.
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But several military sources and the Syrian Observatory for Human Rights, a 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 centres held by the Army of Conquest in Jisr al-Shughur... and Jabal al-Zawiya in Idlib".
- 'Residents afraid' -
In Raqa, where IS militants have carried out some of the mass beheadings that they infamously use as online propaganda, activists and residents said the group cancelled Friday prayers and emptied mosques there 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 regime, but insist Assad must leave power.
Putin, on the other hand, says Assad should stay.
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.
"There is always a risk of getting bogged down but in Moscow they're talking about three to four months of operations," Alexei Pushkov, the head of the foreign affairs committee of Russia's lower house of parliament, told France's Europe 1 radio.
Pushkov 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.
"If you do it in a more efficient way, I think you'll see results," he said.
Syria's foreign minister said Damascus would take part in UN talks aimed at launching formal negotiations on ending its four-year war but will not be bound by their outcome.
Walid Muallem told the UN General Assembly that he understood the talks, proposed by UN envoy Staffan de Mistura, to be "mainly to exchange ideas" and non-binding.
"I would like to announce here that Syria agrees to participate in the four brainstorming committees of experts proposed by the special envoy Staffan de Mistura," said Muallem.