Russian President Vladimir Putin and his Turkish counterpart, Recep Tayyip Erdogan, on Friday agreed to "activate mutual efforts" regarding the situation in northwestern Syrias opposition-run Idlib province, the Kremlin said. "They agreed to activate mutual efforts with the goal of liquidating terrorist threat coming from this region," during a phone call initiated by Erdogan, Agence France Presse quoted the Kremlin as saying in a statement. According to Turkey’s presidency, Erdogan told Putin that Syrian army attacks in northwest Syria are causing a humanitarian crisis and threaten Turkeys national security. Syrian troops have encircled opposition fighters and a Turkish military post in the area in an offensive to reclaim territory and towns they lost early in the war. The military observation post near the town of Morek is one of 12 which Turkey established in northwest Syria under a deal with Moscow and Tehran two years ago to reduce fighting between Bashar al-Assads forces and opposition fighters. In the phone call, Erdogan told Putin that the Syrian army attacks violated a ceasefire in Idlib and damaged efforts for a solution in Syria, Reuters quoted the Turkish presidency as saying. "The president stated that the regimes ceasefire violations and attacks in Idlib are causing a big humanitarian crisis, that these attacks are damaging the solution process in Syria and pose a serious threat to our countrys national security," it said. Erdogan will make a one-day official visit to Russia on August 27, the Turkish presidency said later in another statement. The recent advances by Assads forces have put Turkish troops stationed in the region in the firing line and displaced hundreds of thousands of people, threatening Ankaras hopes of preventing a fresh wave of refugees on its southern border.