Western - backed rebels of the Free Syrian Army(FSA) have rejected an offer of military support from Russia. An FSA spokesman told the BBC that Moscow could not be trusted and that its help was not needed. Foreign Minister Sergei Lavrov said on Saturday that Russia was ready to help the rebels if they attacked militants from the Islamic State (IS) group. Russia, a key ally of the Syrian government, has carried out air strikes in the country since last month. Moscow says the strikes have mainly targeted IS, but Western powers say most have hit the FSA and other factions backed by the West and Gulf states. In his offer to the FSA, Lavrov said the Russian air force could support the FSA provided the US shared information about rebel positions.