Syrian army units and pro-government forces deploy at an undisclosed location in western Syria.

AFP/Paris

France said on 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," Defence Minister Jean-Yves Le Drian told Europe 1 radio, adding that more attacks would follow.

As with a first wave of strikes on September 27, the attacks focused on the IS stronghold of Raqqa in northern Syria.

"We know that in Syria, in particular around Raqqa, there are training camps for foreign combatants whose mission is not to go fight for IS in the Levant but to come to France, to Europe, to carry out attacks," said Le Drian.

He said France's air strikes were complicated by the fact that IS uses human shields.

"IS organises itself in such a way that children, women and civilians are in the frontline," he said.

"The leaders hide in schools, mosques, hospitals, which makes the job of the (international) coalition difficult."

Le Drian criticised Russia's recent involvement in the conflict, saying that "80 to 90%" of its air strikes in Syria were not aimed at IS, but instead at propping up the regime of President Bashar al-Assad, Moscow's long-term ally.

"The Russian military action in Syria over the past 10 days does not target Daesh, their main aim is (to ensure) the security of Bashar al-Assad," said Le Drian.

"We do not consider Bashar part of the solution."

IS jihadists advance on Aleppo: monitor

The Islamic State group advanced to the closest it has been to the Syrian city of Aleppo at dawn on Friday, after hours of ferocious fighting, a monitor reported.

"Dozens of combatants were killed on both sides," said Rami Abdel Rahman of the Syrian Observatory for Human Rights.

After a night of fierce clashes, IS militants had driven out rebels from the localities of Tall Qrah, Tall Soussin, Kafar Qares and the base of Chennaiat al-Mushat by 5:00 am local time, he said.

The seizure of these positions brought the jihadists to about 20 kilometres from the front line where forces loyal to President Assad are positioned, including the Sheikh Najjar industrial zone.