Ankara - World leaders urged "respect for democratic institutions" in key Nato member and European neighbour Turkey as parts of the military launched a coup against President Recep Tayyip Erdogan and violence erupted in Istanbul.The United States, Russia, Nato and the European Union all appealed for stability, with US President Barack Obama calling on all parties in Turkey to back the "democratically-elected" government.Detailing a call between Obama and Secretary of State John Kerry, the White House said both agreed that "all parties in Turkey should support the democratically-elected government of Turkey, show restraint, and avoid any violence or bloodshed".Kremlin spokesperson Dmitry Peskov meanwhile told reporters that Moscow is "deeply concerned" about the situation, with President Vladimir Putin being kept up to date by the foreign ministry and intelligence services."At the moment the quantity of information makes it impossible to clearly define what is happening in the country," he said. "The only priority is to ensure the safety of Russian state institutions and Russian citizens on the territory of Turkey."Russian Foreign Minister Sergei Lavrov had earlier called on Turkey to avoid all "bloodshed" and insisted that the problems in the country be resolved "in accordance with the constitution."Nato chief Jens Stoltenberg called for "calm and restraint, and full respect for Turkey's democratic institutions and its constitution," adding that the country is "a valued Nato ally". The European Union also urged "restraint" in Turkey."Call for restraint and respect for democratic institutions #Turkey," tweeted Federica Mogherini, the EU's foreign policy chief, from a regional summit in Mongolia.Turkey will now likely dominate an EU foreign ministers' meeting on Monday which will also be attended by Kerry.Ankara in March signed a controversial deal with the European Union aimed at stemming migration to the continent, and has recently mended ties with Russia after a major diplomatic crisis.Obama, like other Western leaders, has repeatedly expressed concern about authoritarian steps taken by Erdogan's government.But the country is a key Nato ally and part of the coalition fighting ISIS. The US has military assets at Incirlik Air Base, carrying out strikes in Syria and Iraq.'No impact' on anti-ISIS strikes The ongoing coup attempt is not affecting operations targeting ISIS, and American forces will continue flying missions from a key airbase there, a US defence official said on Friday.The situation "has no impact on counter-ISIL operations from Incirlik Air Base in Turkey", the official said, speaking on condition of anonymity, and using another name for ISIS.German Chancellor Angela Merkel meanwhile called for the "democratic order" in Turkey to be respected, her spokesperson said.German-Turkish relations have come under increasing strain in recent months, with Berlin criticising Ankara's tough line against dissenting journalists and the country's Kurdish minority.Expressing concern, Britain urged its citizens to "avoid public places", according to a statement from the Foreign Office.Iranian Foreign Minister Mohammad Javad Zarif also said his country, which neighbours Turkey, was monitoring the situation with "great concern"."Stability, democracy and the security of the Turks are the priority," Zarif said, according to the Iranian government website, as he stressed "the need to preserve unity" in the country.Iran and Turkey have often been at loggerheads in regional conflicts including Syria, where they back opposing sides in the five-year civil war.Greece, which also neighbours Turkey, said it too was following the situation closely.Television pictures showed tanks deployed outside Atatürk Airport in Istanbul. Reports said that flights into the airport had been halted.Greece's Aegean Airlines confirmed it had cancelled its flights for Saturday to Istanbul and the coastal city of Izmir.