Russian aircraft are delivering military supplies to Syria as well as humanitarian aid, Russian Foreign Minister Sergei Lavrov said on Thursday.

He, however, dismissed concerns of the United States and NATO who recently said that Russia is possibly building up its military presence at Syria's Mediterranean port city of Latakia for potential use of the airfield as a forward air-operating hub.

"Russia is airlifting military products to Syria under existing contracts, as well as humanitarian assistance," Lavrov said, according to TASS.

He also said that Russian military personnel has been in Syria for many years.

"Its presence is linked to the supplies of weapons for the Syrian army, which is bearing the brunt of the war against terrorism, in particular, the Islamic State, and other extremist groups," Lavrov said.

Three Russian military transport planes, including two giant An-124 landed in Syria and new housing units had been set up at the airfield in Latakia which seems to suggest a possible increase in Moscow’s military support for Assad's regime, US officials told AFP on Tuesday.

Russian President Vladimir Putin said last week that it is too early to speak about a possible participation of his country in military operations against the Islamic State group.

Lavrov also spoke about  his phone conversation with his US counterpart, Secretary of State John Kerry, on Wednesday in which Kerry expressed concern over Moscow’s support  for the regime of Syrian President Bashar al-Assad.

Lavrov described as “a colossal mistake” the fact that the US-led international coalition fighting the Islamic State group in Syria “never considered interaction with Syria, not even information exchange.” 

“I cannot comprehend this logic, or rather absolute lack of logic,” Lavrov said, according to rt.com.

Moscow has repeatedly said that its long-time ally Bashar al-Assad should be part of international efforts to combat the jihadist miltants of Islamic State group.