Syrian crisis: Russia vows to intensify air strikes
Russia has pledged to intensify its air strikes against Islamic State targets in Syria, saying the bombing has significantly weakened the militants.
A Russian military official said "panic and desertion" had started among the militants and some 600 "mercenaries" were trying to escape to Europe.
However, Britain said Russia's strikes were supporting its ally, Syrian President Bashar al-Assad.
The West says Russia is also hitting non-IS rebels. Moscow denies the claim.
There have been reports that a number of Syrian civilians have been killed in the Russian air strikes, which began on 30 September.
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?
Inside an air strike - Activist describes "frightening Russian air strike"
Syria's civil war explained - Analysis and background on the conflict
In a statement (in Russian), Col Gen Andrey Kartapolov said Russian aircraft had already made more than 30 sorties with the aim of hitting more than "50 infrastructure targets of the Islamic State terrorist organisation".
"Our intelligence shows that militants are leaving areas under their control. Panic and desertion have started in their ranks," he said.
"Some 600 mercenaries have abandoned their positions and are trying to get to Europe."
Col Gen Kartapolov stressed that because of these results, Russia would now "not only continue but intensify" its air strikes.
In Britain, Prime Minister David Cameron accused Moscow of not "discriminating between IS and the legitimate Syrian opposition groups".
"As a result, they are actually backing the butcher Assad and helping him.
"Rightly, they [Russia] have been condemned across the Arab world for what they have done and I think the Arab world is right about that," Mr Cameron added.
Meanwhile, British Defence Secretary Michael Fallon said military intelligence suggested suggested only one in 20 Russian air attacks so far had been on targets to damage IS.
On Friday, US President Barack Obama said the Russian bombing was driving moderate opposition underground and "only strengthening" IS.
Mr Obama said he rejected the Russian assertion that all armed opponents of the "brutal" Mr Assad were terrorists.
Russia earlier said its aircraft had hit 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.
The air strikes in Syria are Russia's first military engagement outside the borders of the former Soviet Union since the end of the Cold War.
In a statement earlier this week, the US, UK, Turkey and other members of the coalition targeting IS with air strikes called on Russia to cease air strikes they said were hitting the Syrian opposition and civilians, adding that they would "only fuel more extremism".
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.