DAMASCUS, Sept. 4 (Xinhua) -- The Russian warplanes carried out 30 airstrikes on 16 rebel-held positions in the northwestern province of Idlib and nearby rebel-held areas on Tuesday, a monitor group reported.

The Russian air raids took place amid heavy ground shelling by the Syrian army, according to the Syrian Observatory for Human Rights.

The targeted positions lie in a triangle of areas stretching from the western countryside of Idlib to the mountains of the northwestern province of Latakia until the Al-Ghab Plain in the northwestern countryside of Hama Province in central Syria.

The airstrikes targeted 10 areas in Idlib, the last major rebel stronghold in Syria.

They came in response to an allegedly rebel drone attack on Syrian military positions in the Latakia mountains, which killed three soldiers and wounded many others, according to the Russian Defense Ministry.

However, the London-based watchdog said the rebel attack against the government positions in Latakia was not carried out by drones but through artillery shelling.

The Russia- and Iran-backed Syrian army is preparing a wide-scale offensive against the rebels of the al-Qaida-linked Nusra Front, or the Levant Liberation Committee (LLC), in Idlib, the last major rebel stronghold in Syria.

The presidents of Iran, Russia and Turkey are set to hold a summit in Iran's capital Tehran on Friday to discuss the situation in Idlib, where Turkey holds considerable sway over an array of rebel groups.