President Vladimir Putin is flexing his muscle over the military operation in Syria, saying the army should "immediately destroy" any targets threatening Russian forces in the country. "I order to act very tough. Any targets that threaten Russian forces or our infrastructure on the ground should be immediately destroyed," Putin said.

Speaking at a session of the defence ministry's collegium, Putin remarked that the operation in Syria is not in Russia's geopolitical interests. IS (Daesh), he claimed, threatens Russia directly and the campaign is aimed at averting threat to Russia.

The reference is likely to the possibility of IS fighters returning to their Russian homeland to commit terror attacks, and threats further afield as manifested in the Russian Metrojet plane that was blown out of the sky over Egypt's Sinai, killing 224 people.

In an attempt to dismiss critics - who claimed Russia is targeting all forces opposed to Syrian President Bashar al-Assad, and not just Daesh - Putin also said that Russian armed forces are supplying weapons and ammunition to the Western-backed Free Syrian Army (FSA) and providing air support.

Russian defence minister Sergey Shoygu said warplanes have conducted 4,000 combat sorties in Syria, causing serious damage to Daesh infrastructure in the country. Since mid-November, Russia increased the number of aicraft taking part in the operation to 69 and involved strategic bombers in strikes at militants. The focus has been on destroying IS-controlled oil extraction, storage, transportation and refining facilities.

Meanwhile, Kremlin spokesman Dmitry Peskov has said it was up to the Syrian people to discuss the fate of president Bashar al-Assad. Commenting the opposition statement issued after two days of talks in Riyadh, Saudi Arabia, Peskov said: "The fate of Assad should be discussed by Syrians themselves, not Russia.

"Now efforts are focused on drawing up the lists of who to recognize as terrorist organisations, who to consider moderate opposition which can and should be part of the political settlement... Disagreements among certain countries exist. Positions are getting closer," said Peskov.

The conference in Saudi Arabia of political activists and rebel groups agreed on Thursday to set up a joint body to prepare for proposed peace talks with Assad's government but insisted that he leaves office.