Russia has not delivered advanced S-300 missile systems ordered by Syria although several have been built and Damascus has paid a multi-million deposit, Vedomosti daily reported Friday, citing arms industry sources.

A batch of the systems was due to be sent to Syria this spring, according to the Russian arms export agency's contract with Damascus, but the systems are now apparently due for delivery no earlier than the summer of 2014, Vedomosti said.

President Vladimir Putin said in June that Moscow had not yet delivered the sophisticated anti-aircraft missile systems to the Syrian regime for fear of upsetting the balance of power in the region.

Syria ordered four S-300 systems in 2011 at a cost of $1 billion and two sources in the arms industry told Vedomosti that several of the S-300s have already been built, while the production of the others has been postponed.

Syria has paid a deposit of several hundred million dollars, the sources said.

The Russian producer of missiles used in the systems said in April that it had received notice of its contract with Syria being postponed until the summer of 2014, Vedomosti reported.

Syrian Deputy Prime Minister Qadri Jamil said on a visit to Moscow in July that all the contracts to deliver arms from Russia to Syria were still in place.

Russia has angered the West and Arab states that oppose President Bashar al-Assad's regime by refusing to halt military and other cooperation with the Damascus regime throughout the Syria conflict.

Damascus is not expected to push for a quicker delivery of the systems or to demand its deposit back due to Assad's need for Russian support, a source close to Russia's arms export agency told Vedomosti.