EU urges 'respect for democratic institutions' in Turkey

European Union foreign policy chief Federica Mogherini urged "restraint" in Turkey amid an attempted coup against President Recep Tayyip Erdogan.

"In constant contact with EU Delegation in Ankara & Brussels from Mongolia. Call for restraint and respect for democratic institutions #Turkey," she tweeted from a regional summit in Ulan Bator.

Brussels will be watching with deep concern the events in Turkey, a key partner on its southeastern flank which has been trying to join the EU for many years without success.

The EU's controversial deal with Turkey in March to tackle the migrant crisis could be at risk, with implications for French and German elections next year.

Under the deal, Ankara agreed to take back migrants and refugees from the Greek islands and to stop people crossing the Aegean Sea. In return it is to get aid and visa-free travel for 80 million Turks to the EU.

The bloc overcame its aversion to Erdogan's increasingly authoritarian rule, which has received sharp criticism from the 28-nation European Union.

Turkey will now likely dominate an EU foreign ministers' meeting on Monday which will also be attended by US Secretary of State John Kerry.