The majority of Russian military forces in Syria are to begin a withdrawal from tomorrow, President Vladimir Putin has said in a shock announcement.

Mr Putin said that he had ordered the military to begin pulling out of the war-torn country as the intervention had "in large part" achieved its objectives.

Kremlin spokesman Dmitry Peskov said Putin had telephoned Syrian President Bashar al-Assad to inform him of the Russian decision.

Mr al-Assad shortly released a statement saying that he and Mr Putin had agreed to reduce the Russian air force presence in Syria, according to Syrian state television.

Mr Putin said that Russia's Hmeimim airbase in Syria and its Tartus Navy base on the Mediterranean coast of Syria would both continue to operate as normal.

Moscow will maintain a military presence in Syria, and a deadline for complete withdrawal has not yet been announced, according to a report from the Russian government-owned Sputnik news website.

Russia had sent in troops and launched a campaign of air strikes from September last year in support of beleaguered president Bashar al-Assad, who faces challenges from both Islamic State and more moderate rebel groups.

That intervention has helped the government forces to make gains from rebel groups in recent months.

Russia has sought to present itself as joining the international coalition against Isis. However, it has faced accusations that its attacks have largely focused on pounding more moderate groups.