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.