Several EU leaders have criticised Turkey, amid a growing row over the Turkish government’s attempts to hold rallies in European countries.
President Recep Tayyip Erdogan accused Germany and the Netherlands of “Nazism” after officials blocked rallies there.
Dutch Prime Minister Mark Rutte called his comments “unacceptable”, while Germany’s foreign minister Sigmar Gabriel said he hoped Turkey would “return to its senses”.
Denmark’s Prime Minister Lars Lokke Rasmussen has also postponed a planned meeting with Mr Erdogan.
Meanwhile, German ministers also appeared to harden their rhetoric against Turkey.
Germany interior minister Thomas de Maiziere said he was opposed to Turkish political gatherings in Germany, while finance minister Wolfgang Schaeuble said Turkey had “destroyed the basis for further progress in co-operation”.
The rallies aim to encourage a large number of Turks living in Europe to vote ‘yes’ in a referendum expanding the president’s powers.
However, planned rallies in Germany, Austria and the Netherlands were blocked after officials cited security concerns or said the rallies could stoke tensions.
Turkey is holding a referendum on 16 April on whether to turn from a parliamentary to a presidential republic.