Russian Foreign Minister Sergei Lavrov discussed the Syrian conflict with US Secretary of State John Kerry on Wednesday, TASS reported.

Russia’s Foreign Ministry said the telephone conversation focused on the problem of peace settlement of the conflict in Syria as well as certain aspects of Russia-US relations. 

A Foregn Ministry official said that Lavrov “once again highlighted the significance of a consolidated rebuffing of terrorist groups” that have seized large parts of the Syrian territory and are threating international security, according to TASS.

The discussion of the Syrian conflict between Kerry and Lavrov – the second one in the last four days - comes amidst increased US concerns about reports suggesting Moscow is possibly building up its support for Syrian President Bashar al-Assad's regime.

US officials on Tuesday said three Russian military cargo aircraft had landed in Syria in recent days, and that new housing units had been set up at the airport in Latakia, according to AFP. Russia denies its activities in Syria go beyond its known deliveries on commercial contracts with the country and its usual activities at the naval base in Tartus.

In a phone conversation with Lavrov on Saturday, Kerry made clear that if such reports were accurate,” these actions could further escalate the conflict, lead to greater loss of innocent life, increase refugee flows and risk confrontation” with the US-led international coalition battling Islamic State group in Syria, the State Department said back then.