Turkey is calling on Russia and Iran to pressure the Syrian government to halt its offensive in rebel-held northwestern province of Idlib. Turkish Foreign Minister Mevlut Cavusoglu said Russia and Iran must fulfil their duties under a joint accord which announced a "de-escalation zone" in Idlib. He said the Syrian army's advances could not have taken place without the support of Moscow and Tehran. Both countries back President Bashar al-Assad in the six-year conflict. Nearly 3 million people are believed to be in the region. Fresh conflict could trigger more displacement on neighboring Turkey's border.