Russia's military intervention in Syria is propping up Bashar Assad rather than tackling Islamic State (IS), Defence Secretary Michael Fallon has claimed.
He said the "vast majority" of strikes since Russian president Vladimir Putin began the action had not been aimed at IS jihadists but were instead "killing civilians" and the Free Syrian forces rebelling against Assad's regime.
Mr Fallon acknowledged the Russian involvement had "complicated" the situation but indicated he still believed that Britain should extend its own bombing campaign to target IS in Syria.
In an interview with the Sun he said initial Ministry of Defence intelligence suggested only one in 20 Russian air strikes so far were on targets to damage IS.
He said: "We're analysing where the strikes are going every morning. The vast majority are not against IS at all.
"Our evidence indicates they are dropping unguided munitions in civilian areas, killing civilians, and they are dropping them against the Free Syrian forces fighting Assad.
"He's shoring up Assad and perpetuating the suffering."
Mr Fallon denied that Russia's involvement had left Europe and the US looking weak.
"I don't accept he has outmanoeuvred us. He has complicated the situation in Syria. But we're not powerless."
He indicated that the changed circumstances would not prevent the Government pressing ahead with making the case to extend the RAF's strikes against IS from Iraq into Syria.
It would be "morally wrong" not to target IS in Syria, he said, adding: "We can't leave it to French and Australian, American aircraft to keep our own British streets safe."
A statement issued by the governments of the the UK, US, France, Germany, Qatar, Saudi Arabia and Turkey condemned the Russian involvement, stating it did not target IS - also known as Daesh or Isil.
They said: "We express our deep concern with regard to the Russian military build-up in Syria and especially the attacks by the Russian Air Force on Hama, Homs and Idlib which led to civilian casualties and did not target Daesh.
"These military actions constitute a further escalation and will only fuel more extremism and radicalisation.
We call on the Russian Federation to immediately cease its attacks on the Syrian opposition and civilians and to focus its efforts on fighting Isil."
A former senior military adviser claimed the UK's policy in Syria has been hampered by "wishful thinking" about what would happen to Assad's regime.
In an interview with BBC2's Newsnight Lt Gen Sir Simon Mayall painted a picture of a UK being in a strategic muddle over Syria and described Russia's intervention as "hugely significant".
He described the UK's response as "inadequate" when faced with the scale of the IS advance.
"If we genuinely want to stop this and reverse it," he said, "we are going to have to do more than have high-flown rhetoric because this is a really seriously dangerous situation on the ground ... and our response frankly is inadequate for the scale of the problem that we've got."