The Syrian regime believes its "victory" over the rebellion is assured, thanks to Moscow and its other allies' support, Foreign Minister Walid Muallem said in a letter to his Russian counterpart Sergei Lavrov.

"Syria's unwavering confidence in its victory is thanks to its people's resistance, and to the support of its friends, especially Russia," said Muallem in his letter, sent to mark the 70th anniversary of the opening of diplomatic relations between the two countries.

"The leaders and people of Syria are respectful and full of gratitude for Russia's stance," said Muallem, adding that Moscow "is supporting Syria in the face of a world war launched by obscurantists and terrorists".

President Bashar Assad's regime has consistently refused to recognise the existence of any genuine popular revolt seeking his ouster, and has instead blamed all violence in Syria on a foreign-backed "terrorist" plot.

Syria's war, which began as a peaceful movement for change but later grew into an armed rebellion after the army unleashed a brutal crackdown against dissent, has killed more than 170,000 people.

"Syria is more determined than ever to crush the terrorists and to defend its sovereignty... and the security of the region," said Muallem.

Like China, Russia has blocked three U.N. Security Council draft resolutions that would have imposed sanctions on the Syrian regime.