DAMASCUS, Syria (AP) — Government forces advanced Monday under the cover of Russian airstrikes toward an air base besieged by the Islamic State group in northern Syria, a Syrian military official and activists said, while a rebel military commander was killed in another battle in a nearby area.

The offensive in the northern province of Aleppo aims to lift the siege that IS has been imposing on the Kweiras military base since 2014. Jihadis have launched several attacks over the past weeks in an attempt to capture the base but were not able to.

The army captured the village of Bkayze, about seven kilometers (four miles) from the air base, the military official said, speaking on condition of anonymity in line with regulations. Troops also captured two other villages near the base, Aleppo-based activist Maamoun al-Khatib told The Associated Press.

"It will be a moral victory for the regime if they are able to lift the siege imposed on Kweiras," said Syrian activist Ahmad al-Ahmad, who is currently in Turkey.

In another battle in Aleppo province, Syrian troops and pro-government gunmen killed the military commander of one of the most powerful rebel factions in northern Syria, according to the Britain-based Syrian Observatory for Human Rights, an activist group that monitors the Syrian war through a network on the ground.

Hezbollah's Al-Manar TV identified the dead commander as Ismail Nassif, with the Noureddine Zengi rebel group. The Observatory and Al-Manar gave no further details.

Since Russian airstrikes began on Sept. 30, Syrian troops have been on the offensive on several fronts in an attempt to secure supply routes and regain control of strategic areas.

In Moscow, the Russian Defense Ministry said that its jets have conducted 33 sorties, hitting 49 targets in the past 24 hours in the provinces of Aleppo, Damascus, Idlib, Latakia and Hama. Among the targets, it said, were underground facilities, a workshop producing homemade missiles and a training camp.

Moscow says its airstrikes on Islamic State positions outside the capital Damascus are forcing the militants to flee. The ministry said that its drones flying overnight showed several groups of militants, about 100 people in each of them, leaving their positions in Marj al-Sultan.

In Lebanon, troops fired artillery on a vehicle carrying militants on the outskirts of the Lebanese border town of Arsal, inflicting casualties, a Lebanese military official said, speaking on condition of anonymity in line with regulations.

In a nearby informal camp housing Syrian refugees, four people were killed and several wounded in an explosion, the state-run National News Agency said, without giving a cause for the blast.

Lebanese troops regularly shell militants' positions in the areas near the Syrian border where jihadis captured last year some 20 troops and policemen in a cross-border attack, killing four and still keeping the others captive.

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Associated Press writer Nataliya Vasilyeva contributed to this report from Moscow.