Air strikes hit near a Turkish military position on Wednesday in northwest Syria, where the Russian-backed army has waged a fierce offensive against rebels, a monitor and local activists said.
A senior Turkish security source told Reuters there were heavy clashes between Syrian government forces and rebel fighters about 500 metres from the Turkish observation post.
"However, the conflict is taking place very close by and it is violent. Syrian forces bombed rebel positions," the source said.
It was not immediately clear whether the Turkish position was the target, but the source said Turkish soldiers were not affected.
President Vladimir Putin said on Tuesday that Russia and Turkey had agreed steps to tackle militants in northwest Syria and "normalise" the situation there.
Putin and Turkish President Tayyip Erdogan held talks in Moscow after Syrian army troops encircled another Turkish military post in the town of Morek in earlier this month.
- Russia in Talks With Turkey to Sell Advanced Su-57 Stealth Fighter Jet
- Syrian Rebels Push Back Against Russia-backed Syrian Army Advances in Idlib
- During Russia Visit, Turkey Will Ask Putin to Curb Syrian Army
Syrian President Bashar al-Assad, backed by Russian air power, has gained ground from insurgents this month in the northwest, the country's last big insurgent stronghold.
Talks between Moscow, Assad's key ally, and Ankara, which backs some rebel factions, have not managed to end fighting in Idlib.
Turkey set up 12 observation posts in the Idlib region in Syria's northwest under a deal with Moscow and Tehran two years ago.
Local activists who track warplanes in opposition territory said air strikes pounded positions around the Turkish post in Sher Maghar village at the edge of Hama and Idlib province.
Photos they shared showed large clouds of grey smoke rising from the rural area.
The Syrian Observatory for Human Rights, a UK-based war monitoring group, said heavy air strikes also hit other villages and towns in Idlib.