(CNN)A diplomatic feud between Turkey and the Netherlands continued to escalate Sunday, with Turkish President Recep Tayyip Erdogan accusing its NATO ally of "sacrificing Turkish-Dutch relations" and Denmark stepping into the fray.
The dispute erupted on Saturday after the Netherlands barred a plane carrying Turkey's foreign minister from landing in the country. Foreign Minister Mevlut Cavusoglu had planned to address Turkish expatriates in support of an upcoming referendum that would expand Erdogan's powers.
The Netherlands said it canceled the flight because of concerns about public order at the gathering. But Erdogan took it as a slight, accusing the Dutch of Islamophobia and comparing them to Nazis.
A similar spat between Erdogan and Germany happened a week ago.
Turkey's President Recep Tayyip Erdogan talks during a rally in Istanbul on Sunday.
Driving the disputes is Turkey's referendum next month that would change its government structure. Turkish officials want to rally supporters among expatriates in Europe, but some countries have resisted.
This month, Germany canceled Turkish rallies there. Erdogan accused the government of Nazism, leading to a sharp rebuke from Chancellor Angela Merkel.
With the Netherlands heading for a nationwide vote Wednesday -- with concerns about Muslim immigration a central issue.
"I thought Nazism was over but I was wrong," Erdogan said at the International Goodness Awards ceremony in Istanbul on Sunday.
"What we saw in the last couple of days in Germany and Netherlands are the reflections of Islamophobia."
Denmark postpones meeting with Turkey
Later Sunday, Danish Prime Minister Lars Løkke Rasmussen postponed a discussed visit by his Turkish counterpart.
"Under normal circumstances it would be a pleasure for me to greet Prime Minister (Binali) Yildirim in Copenhagen," Rasmussen said. "But with the current rhetorical attacks by Turkey against the Netherlands, a new meeting cannot be seen isolated from that."
The Danish government is observing developments in Turkey "with great concern as democratic principles are under considerable pressure," he said.
"A meeting right now would be interpreted as if Denmark is viewing developments in Turkey more mildly, which is not at all the case."
The prime minister's office said Danish representatives and Turkish officials had been discussing the possible meeting for several weeks. It would have been scheduled for later this month in Denmark.
Protests in the Netherlands and Turkey
On Saturday, protests broke out in Rotterdam and in the major Turkish cities of Ankara and Istanbul, after the Netherlands blocked Cavusoglu's flight.
Protesters in Rotterdam took to the streets Saturday.
Erdogan reacted angrily. "They are timid and cowards," he said. "They are Nazi remnants and fascists."
'We will respond in the heaviest way'
Turkey's April 16 referendum vote on its constitution would turn Turkey's parliamentary system into a presidential one, effectively consolidating the power of three legislative bodies into one executive branch under Erdogan.
Some 1.5 million Turkish nationals living in Germany are eligible to vote in the referendum, according to Turkish news agency Anadolu.
In the Netherlands, far-right politician Geert Wilders praised the decision to bar the Turkish minister and credited his own party for the decision.
