Sweden must cut its ties with a Syrian Kurdish militia or Turkey will continue to block its application to Nato, Ankara’s ambassador to Stockholm has warned amid a deepening crisis over the Scandinavian country’s bid to join the transatlantic defence alliance.

Emre Yunt told the Financial Times that severing links with the People’s Protection Units (YPG) was “the most important” of Turkey’s demands after president Recep Tayyip Erdo?an stunned his Nato allies by saying he could not accept the membership of Sweden and Finland due to their support for groups that Turkey views as terrorists.

Erdo?an, who on Wednesday blocked Nato’s initial decision to process requests by the two Nordic countries to join the military alliance, lambasted them for refusing Turkish requests to extradite 30 people accused of having links to terror groups.