Russian bombers launched a third day of air strikes against militants in Syria from an Iranian air base, the Russian defence ministry said on Thursday.

The ministry said Tu-22M3 long-range bombers and Su-34 fighter bombers struck Islamic State targets in the Syrian province of Deir al-Zor.

It said the military aircraft had taken off from bases in both Russia and Iran and destroyed six command posts and a large number of fighters and military equipment.

All the Russian planes returned to base after the strikes, the defence ministry said.