Turkish Family Minister Fatma Betul Sayan Kaya flew back to Istanbul on Sunday after being expelled from the Netherlands and escorted back to Germany, describing the Dutch treatment as "ugly."

"We were subjected to rude and tough treatment... Treating a female minister this way is very ugly," Kaya told reporters at Istanbul's Ataturk airport. "As a minister holding a diplomatic passport, I don't have to get permission to come together with our citizens at our consulate, which is considered Turkish territory," said Kaya.

Kaya tried to enter the Turkish consulate in Rotterdam on Saturday to address Turkish émigrés to drum up support for next month's referendum to dramatically expand President Recep Tayyip Erdogan's powers.

Police prevented her from entering the compound, triggering hundreds of Turkish flag waving protestors to gather demanding to see her. Twelve people were arrested for public order offenses as protestors threw bottles and rocks at police, who used batons, dogs and water cannon to put down the riot.

The Dutch government said it had warned the Turkish government that the family minister would not be allowed into the consulate.

The confrontation capped an intense day in which the Netherlands refused permission for Turkish Foreign Minister Mevlut Cavusoglu's plane to land in Rotterdam to address the Turkish diaspora at the consulate.

Dutch Prime Minister Mark Rutte said Sunday that Cavusoglu's comments before departing, in which he threatened political and economic sanctions on his government, had made the trip impossible.   

"We can never do business under this kind of blackmail," he said.

Dutch officials said they withdrew his plane's permission to land because of "risks to public order and security." The government had repeatedly said it was not appropriate for Turkish officials to campaign in the Netherlands over concern that tensions over the highly divisive referendum would impact the Dutch-Turkish community.

Turkish Prime Minister Binali Yildirim on Sunday threatened "strong countermeasures" against the Netherlands. 

Erdogan repeated comments made a day earlier, accusing the Dutch government of "Nazism and fascism."

The comments were repeated by several Turkish ministers and plastered on the front pages of pro-government newspapers.

As the war of words escalated, hundreds of flag waving protestors on Saturday and Sunday gathered in front of the Dutch consulate in central Istanbul, some shouting "Allahu Akbar" (God is Great) and flashing ultra-nationalist hand signs.

CNN Turk showed video footage of a protestor scaling the consulate's roof and replacing the Dutch flag with a Turkish flag.

DW journalist Kate Brady said Erdogan supporters returned to the Turkish consulate in Rotterdam on Sunday.

The diplomatic spat comes ahead of a March 15 election in the Netherlands, where right-wing, anti-immigration politician Geert Wilders is running neck and neck with Rutte's party. But even if Wilders comes out on top, none of the mainstream parties will enter a coalition with him.

Wilders has sought to capitalize on the tensions. In a tweet to Erdogan and Cavusoglu, he accused the two of being "Islamofascists."

Yildirim said on Sunday he believed the Dutch government's moves were in part related to the upcoming election.

"We think that because of the election the situation witnessed today stems from domestic politics, but whatever the case it is absolutely unacceptable and we will certainly respond in a strong manner," CNN Turk quoted him as saying.

The banning of Turkish referendum campaigning in Rotterdam follows similar moves by several cities across Europe, including in Germany. 

The proposed constitutional changes to expand Erdogan's powers would be a "dangerous step backwards" for democracy, a panel of legal experts from the Council of Europe said on Friday. 

cw/rc (AFP, AP, dpa, Reuters)