ISTANBUL - An attack on Syria's Idlib, a rebel-held enclave, would be a massacre and the upcoming summit in Tehran, which will be attended by Iran, Russia and Turkey, would yield positive results, Turkish President Tayyip Erdogan was quoted as saying by Hurriyet Daily.Russia, an ally of Syrian President Bashar al-Assad, resumed air strikes on Tuesday against insurgents in Idlib. This followed weeks of aerial bombardment and shelling by pro-Syrian government forces in an apparent prelude to a full-scale offensive against the rebels' last major enclave."The situation in Idlib is crucial for Turkey. A ruthless process has been going on there. ... God forbid, if this area is hailed by missiles there would be a serious massacre," Erdogan was quoted as saying.Turkey, which has backed some rebels against Assad, is hoping for a positive outcome from the summit in Tehran which will be held later in the week."We will carry this issue to a positive point with the Tehran summit, which is a continuation of Astana. I hope we will be able to prevent the Syrian government's extremism in this region," Erdogan said, according to Hurriyet.Speaking to reporters on the plane back from an official visit to Kyrgyzstan, Erdogan said the road map for the northern Syrian city of Manbij agreed between Ankara and Washington in June is not going forward on the same path, according to Hurriyet.Under the road map for Manbij agreed by the two NATO allies, Turkish and US forces are now carrying out joint patrols there to clear the area of YPG militants."We are not at an ideal point (about Manbij). Unfortunately the agreement made is not going forward in the same direction as the initial discussions," Erdogan was quoted as saying.In a meeting on Tuesday, Turkish Defence Minister Hulusi Akar and the US special representative for Syria, James Jeffrey, discussed the developments in Syria.