France said Friday it had carried out a second wave of strikes overnight on Islamic State targets in Syria and accused Russia of failing to target the group.

"Two Rafale jets dropped bombs on an IS training camp. The objectives were accomplished," Defense Minister Jean-Yves Le Drian told Europe 1 radio, adding that more attacks would follow.

Regime forces advanced Thursday in western Syria in a "vast offensive" against armed opposition groups, as NATO voiced alarm at escalating Russian military activity in the war-torn country.

Moscow has dramatically stepped up its nine-day-old air war against foes of President Bashar Assad, with heavy bombing by warplanes and cruise missile strikes from the Caspian Sea.

U.N. Secretary-General Ban Ki-moon has warned that the involvement of Hizbullah and other Lebanese fighters in the war in Iraq and Yemen puts more dangers on Lebanon.

In his report to the Security Council on the implementation of Resolution 1559, Ban also said that the participation of Lebanese nationals in the conflict in Syria is in violation of Lebanon's dissociation policy.

Russia dramatically escalated its air war in Syria Wednesday, unleashing heavy bombardments and cruise missile strikes from the Caspian Sea as cover for a major Syrian army ground offensive against rebels.

Russian President Vladimir Putin said Moscow had begun synchronizing its strikes with the army's ground movements as the Kremlin voiced willingness to make contact with Western-backed rebels that Washington and its allies accuse it of targeting. 

French President Francois Hollande did not suggest forming an alliance between Syrian President Bashar Assad's forces and the moderate opposition Free Syrian Army, an aide said Wednesday, contradicting comments by Russian leader Vladimir Putin.

"The president spoke of the necessary presence of the Syrian opposition around a future negotiating table. The rest is not a French idea," a member of Hollande's entourage told reporters during a visit to Strasbourg.

Turkish Prime Minister Ahmet Davutoglu Wednesday said only two Russian air strikes in Syria had targeted Islamic State jihadists and warned that Ankara would not make any concessions about the security of its borders.

His comments came after Russian warplanes twice violated the airspace of key NATO member Turkey in the last days.

Russian military officials were to hold talks with their Israeli counterparts in Tel Aviv on Tuesday after the countries' leaders agreed to establish a mechanism to avoid accidental clashes in Syria.

Israel's military confirmed the two-day meeting on "regional coordination," which comes after Prime Minister Benjamin Netanyahu and Russian President Vladimir Putin held talks last month related to Syria.

Turkish President Recep Tayyip Erdogan and EU head Donald Tusk said Monday they had discussed Ankara's controversial plan for a safe zone cleared of Islamic State jihadist fighters in northern Syria.

"The European Union is ready to take up all issues with Turkey so we also discussed a possible buffer zone in Syria," Tusk said after meeting Erdogan for talks in Brussels dominated by the migrant crisis and the Syrian conflict.

More than 40 of Syria's most powerful rebel factions said on Monday that Russia's air campaign had made a political solution to the country's bloody conflict impossible.

In a statement posted online, 41 groups including Jaish al-Islam near Damascus, Ahrar al-Sham in northwest Syria, and the Northern Front said that Russia's "brutal occupation has cut the road to any political solution".

Germany voiced doubt Monday about Russia's claims that it was targeting Islamic State jihadists rather than moderate rebels with its air strikes in Syria.

"About the... continuing Russian air strikes: We would consider it important to reconcile words and actions," said foreign ministry spokesman Martin Schaefer.