Russia has reportedly deployed tanks and artillery in Syria to support the regime of President Bashar al Assad.

Speaking on condition of anonymity, a US official said on Monday seven Russian T-90 tanks and an undisclosed number of artillery were seen at an airfield near the port city of Latakia, a stronghold of the dictator.

“It appears, and all the indications are pointing, that [the deployment was] for airfield defence,” the official said.

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Last week, Russia sent military hardware and troops to bolster the Syrian army, which is fighting Islamic State terrorists and anti-Assad rebels.

Moscow confirmed it had “experts” on the ground but refused to give further details about its military presence in the country.

Syrian President Bashar al Assad with Russian Leader Vladimir Putin.

Syria’s ambassador to Moscow said talk of Russian troops on the ground was “a lie”.

Russian assistance for Mr Assad could complicate the US-led coalition’s air strikes against the Islamic State Group (IS) jihadists in Syria, the US official claimed.

Defence officials were also concerned about the possibility of accidents if coalition and Russian planes operated in the same airspace.

Two Russian transport planes, purportedly carrying humanitarian aid, landed in Syria on Saturday, Russian state media.

The United States, Canada, Turkey and Gulf states have been bombing IS targets in Syria. This coalition will soon be joined by Australian and French military jets.

Some commentators have warned these joint air forces could accidentally come into contact with Russian troops, with consequences for international diplomacy.

– with AAP