Syria conflict: Russia air strikes stepped up
Russia has stepped up its campaign of air strikes against opponents of Syrian President Bashar al-Assad.
Moscow said its aircraft had hit Islamic State (IS) command centres, arms depots and military vehicles.
Targets included the IS stronghold of Raqqa, but also Aleppo, Hama and Idlib - provinces with little IS presence.
Members of the US-led coalition targeting IS have renewed their criticism of the Russian action.
In a statement, the US, UK, Turkey and other coalition members called on Russia to cease air strikes they said were hitting the Syrian opposition and civilians, adding that they would "only fuel more extremism".
The Syrian opposition and others have suggested non-IS rebel factions opposed to President Assad - the Kremlin's ally - are bearing the brunt of the Russian attacks.
Alexei Pushkov, the head of the foreign affairs committee in Russia's parliament, said the air strikes - which began on Wednesday - could last for three to four months.
He added that the US had only "pretended" to bomb IS, and promised that Russia's campaign would be much more effective.
Russian air strikes - in depth
Where key countries stand - Who is backing whom
Why? What? How? - Five things you need to know about Russia's involvement
What can Russia's air force do? - The US-led coalition has failed to destroy IS. Can Russia do any better?
Media offensive - What does the campaign look like through the lens of Russian media?
Inside an air strike - Activist describes "frightening Russian air strike"
The British-based Syrian Observatory for Human Rights said Russian air strikes had hit a training camp and a camouflaged command post near the IS "capital" of Raqqa, and that 12 IS fighters were killed in the attack.
Activists and residents of the city said IS had cancelled Friday prayers and emptied mosques, amid fears of further Russian air strikes.
Elsewhere, a radio mast and communications tower belonging to the Free Syrian Army - forces opposed to President Assad which have received American training and supplies - were attacked by Russian aircraft in Aleppo. However, Syrian sources said neither had been destroyed, contrary to earlier reports.
Meanwhile, IS fighters have attacked a government airbase in eastern Syria.
Reports from the area, near the IS-controlled city of Deir al-Zour, speak of loud explosions, heavy clashes and government fighter jets circling in the sky.
The US-led coalition said it had targeted IS in 28 air strikes in both Syria and Iraq on Thursday.
The warning from members of the US-led coalition came as the French, German and Russian leaders met in Paris. The meeting was called to discuss peace efforts in Ukraine, but were overshadowed by Syria.
French President Francois Hollande said he had reminded his Russian counterpart Vladimir Putin that air strikes in Syria should hit IS targets alone.
German Chancellor Angela Merkel, speaking alongside Mr Hollande after the summit, said: "Both of us insisted on the fact that IS is the enemy that we should be fighting."
Analysis: Frank Gardner, BBC security correspondent
The entry of Russia into the Syrian conflict, albeit in the air not on the ground, will be a perfect recruiting sergeant for IS.
The propaganda videos are doubtless already being prepared. The Russians are, after all, the same historic enemy fought by the Mujahideen in Afghanistan throughout the 1980s and eventually defeated (with US, Saudi and Pakistani help).
The prospect of Russian pilots attacking Muslim fighters on the ground will be embarrassing to Arab governments who will not want their air forces to be seen as on the same side.
The result is likely to be more recruits joining the extremists of IS and al-Nusra, both from within Syria and from outside the region.
The strikes in Syria are Russia's first military engagement outside the borders of the former Soviet Union since the end of the Cold War.
Russian Foreign Minister Sergei Lavrov, speaking at the UN in New York, said Russia would also fight other terrorist groups including the al-Nusra Front - an al-Qaeda affiliate.
He said this position was the same as that of the US-led coalition, which has been carrying out air strikes in Iraq and Syria for the past year.
"We are not supporting anyone against their own people. We fight terrorism," he said.
Mr Lavrov said the targets were selected "in co-ordination with the Syrian army".
Syrian Foreign Minister Walid Muallem, speaking at the same meeting, said air strikes alone were not enough to defeat IS but described the Russian action as "effective'' because it supported his country's efforts to combat terrorism.
He also said his country's army was "capable of cleansing the country of those terrorists".
Syria's civil war
Why is there a war in Syria?
Anti-government protests developed into a civil war that four years on has ground to a stalemate, with the Assad government, Islamic State, an array of Syrian rebels and Kurdish fighters all holding territory.
Who is fighting whom?
Government forces concentrated in Damascus and the centre and west of Syria are fighting the jihadists of Islamic State and Jabhat al-Nusra, as well as less numerous so-called "moderate" rebel groups, who are strongest in the north and east. These groups are also battling each other.
What's the human cost?
More than 250,000 Syrians have been killed and a million injured. Some 11 million others have been forced from their homes, of whom four million have fled abroad - including growing numbers who are making the dangerous journey to Europe.
How has the world reacted?
Iran, Russia and Lebanon's Hezbollah movement are propping up the Alawite-led Assad government, while Turkey, Saudi Arabia and Qatar back the more moderate Sunni-dominated opposition, along with the US, UK and France. Hezbollah and Iran are believed to have troops and officers on the ground, while a Western-led coalition and Russia are carrying out air strikes.