A map shown by the Russian military on state television appears to show that some Russian artillery contingents could be operating on the ground in central Syria's Homs region.
Russia has servicemen at bases in government-held Syria helping to conduct an air campaign in support of forces loyal to President Bashar al-Assad but denies it has deployed ground troops.
The detailed map shown in footage during a defence ministry briefing with President Vladimir Putin Tuesday showed acronyms for Russian contingents near areas where the regime is conducting an offensive against jihadists.
The diagram, shown to Putin on a large screen and filmed by state television, apparently showed that several 152mm-calibre Msta (2A65) howitzers of the 120th artillery brigade are deployed close to the town of Sadad, about 60 kilometres (40 miles) south of Homs.
A Syrian military source told AFP only that "there are Russian counselors in Sadad advising the Syrian army on the artillery."
The 120th artillery brigade is based in Russia's Kemerovo region.
Kremlin spokesman Dmitry Peskov on Wednesday reiterated Moscow's consistent denial that it has deployed any ground troops in Syria.
"There is a technical contingent linked to ensure the operation of the Russian air force," Peskov said.
"There are no ground troops there and Russia soldiers are not conducting a ground operation there," Peskov said.
He said he was not a "specialist of military maps" and directed all questions on the one shown on television to the defence ministry.
Russia's defence ministry did not reply to repeated requests from AFP to comment.
Russia has been bombing targets in Syria since September 30, and said it would step up its air campaign after confirming Tuesday that a bomb brought down a Russian jet in Egypt last month.
At Tuesday's briefing with Putin, the head of Russia's general staff Valery Gerasimov gave a detailed account of the ground offensive in Syria, saying it is conducted by both the Syrian army and pro-government militias.
"In the central part of the country, as a result of the offensive by government troops and militia contingents, it has become possible to take Khadat under control and block the militants in Maheen," he said, referring to a town southeast of Sadad.