Islamic State has seized control of several villages north of Aleppo, Syria, despite Russian and US air strikes said to be targeting the group.

Moscow says its air force has killed 300 militants over the past 24 hours.

But a BBC correspondent in the area says the strikes seem to be mostly hitting rival rebel groups, allowing Islamic State (IS) to push forward.

A commander of Iran’s Revolutionary Guards working with the Syrian army fighting IS has also been killed.

Iran blames IS for the killing of Gen Hussein Hamedani on Thursday, but the exact circumstances remain unclear.

Dozens of fighters have been killed on both sides as Islamic State advanced north of Aleppo on Friday, the London-based Syrian Observatory for Human Rights said.

IS has driven out opposition forces from a number of villages, as well as a military base, the observatory’s Rami Abdel Rahman told the AFP news agency.