A senior aide to Russian President Vladimir Putin has defended his government's right to supply arms to Syria.
Yuri Ushakov said on May 31 that Moscow will fulfill its existing arms contracts with Damascus as they do not include any weapons that fall under international bans.
However, Ushakov added that Russia is unlikely to conclude any new arms deals with Syrian President Bashar al-Assad's regime.
He criticized a recent European Union decision not to renew an embargo on weapons for Syria's opposition.
Russia is one of Assad's staunchest backers and its main supplier of weapons.
Earlier in the day, Russian military aircraft manufacturer MiG said it will likely honor contracts to deliver modern fighter jets to Assad's government.
MIG Director-General Sergei Korotkov told journalists that Russia is holding negotiations with a Syrian delegation to supply Damascus at least 10 MiG-29 planes.
The news follows earlier Russian media reports saying Moscow may not deliver advanced S-300 air-defense missile systems to the Syrian regime this year.
The "Vedomosti" daily quoted a defense source as saying it was unclear if the weapons would be delivered this year.
The "Kommersant" daily quoted its source as saying delivery was only planned for 2014.
An unnamed Russian arms industry source was quoted by Interfax news agency on May 31 as saying that Moscow is unlikely to deliver a shipment of S-300 antiaircraft missiles to Syria before the autumn.
The source also suggested that the timing of the delivery of the missiles would depend on the development of the situation in Syria.
The comments came as Assad appeared to imply on May 30 in an interview with Lebanon's Hizballah-owned Al-Manar television that Russia had already delivered some of the missile systems.
The delivery of advanced antiaircraft missile systems to Assad's regime has caused concern among Western nations and was described by analysts as a "game-changer."
Assad also warned that Damascus would retaliate for any future Israeli air strike on his territory, and hinted at an anti-Israeli offensive in the Golan Heights.
There was no immediate comment on Assad's remarks from Israel, which has been occupying the Golan Heights since the 1967 Arab-Israeli War.
Assad also reiterated that the Syrian government is willing in principle to attend a peace conference in Geneva, but said any agreement would have to be put to a referendum.
The Syrian National Coalition announced at a meeting in Turkey this week that it would not attend the conference as it deals with internal divisions.
According to UN estimates, more than 80,000 people have died in the two-year Syrian civil war.
Based on reporting by AFP, Reuters, AP, dpa, and Interfax