Russian President Vladimir Putin on Tuesday defended Moscow's arms sales to the Syrian government, but denied that the advanced S-300 systems had already been delivered.

Putin told a news conference after a summit with European Union leaders that Russia did not want to upset the military balance in the region and all its arms sales to Syria were inline with international law.

The president's remarks confirm a Russian newspaper report last Friday that Moscow was set to deliver the first shipment of S-300 air defense missiles to President Bashar Assad's regime in 2014. The confusion comes after Assad told Hezbollah's Al-Manar television station in an interview last Thursday that his regime had already received the first shipment.

"Syria has got the first batch of Russian S-300 missiles ... The rest of the shipment will arrive soon," Assad was quoted as saying in excerpts of the interview released Thursday morning.

According to Russia's Vedomosti newspaper, a source in the Russian defense industry has said it is unclear if the S-300s would reach Syria this year. The Kommersant daily, meanwhile, cited a source as saying that the missiles would reach the Assad regime in the second quarter of 2014.

Both of the sources quoted by the two dailies said that no missiles had been delivered so far. The contract for the S-300 shipment was finalized in 2010. Vedomosti said the contract is worth $1 billion, AFP said.

Additionally, Vedomosti's source said that although Moscow is publicly stating that the contract will be honored, and the shipment delivered, there is no guarantee that this will actually happen.

In another report, a Russian arms industry source told Interfax news agency last Friday that Moscow was unlikely to deliver the missiles to Syria before the autumn.

The source suggested the delivery could be accelerated if neighboring countries carried out air attacks on Syria or if a no-fly regime were to be imposed on the country.