Russia's Syrian bombing campaign against forces opposing Bashar al-Assad has only served to help the Islamic State (Isis), according to Philip Hammond. The British foreign secretary made the accusations to MPs in the House of Commons on 16 December.

The foreign secretary claimed that the majority of the Kremlin-ordered attacks were aimed at groups like the Free Syrian Army rather than Isis and the jihadists have been able to gain more ground in Syria because of Russia's actions.

"It is unacceptable that Russian action is weakening the opposition, and thus giving advantage to the very Daesh (Isis) forces that they claim to be engaged against," Hammond said. The comments come after MPs voted to back David Cameron's plan to bomb Isis targets in Syria.

The prime minister argued ahead of the Commons vote that there were 70,000 non-Islamist fighters ready to take on Isis. But the figures has been questioned and even the Mayor of London Boris Johnson said it could have been "exaggerated".

Hammond's warning also comes after Cameron said there were "some signs" Russian forces were concentrating more on Isis targets in Syria after the prime minister spoke to Vladimir Putin at a November G20 Summit in Turkey. But the prime minster admitted that there was still a rift between the UK's stance and Russia's on the civil war.

"On Syria, it's vital that we do more for those in humanitarian need, that we find a political solution to this conflict and that we degrade and destroy Isis," he said.

Saudi Arabia announced on 15 December that a new 34-nation-strong Islamic military alliance, including Egypt, Qatar, the United Arab Emirates and Turkey, will be formed in a bid to fight terrorist groups in the region.