Hackers supporting Turkish President Recep Tayyip Erdogan today defaced Twitter accounts of top individuals and institutions with Nazi jibes, as the EU hit back at Ankara's behaviour in an escalating crisis.
Turkey and the European Union are going through their most explosive crisis after key EU members The Netherlands and Germany blocked Turkish ministers from holding rallies to back constitutional changes expanding Erdogan's powers.
Erdogan has repeatedly accused the two countries of behaving like "Nazis", comments that have left The Hague and Berlin aghast.
EU chiefs today blasted his comments as "detached from reality" and incompatible with Turkey's ambitions to join the bloc.
The strong reaction from Brussels came as The Netherlands was voting in an election where Prime Minister Mark Rutte is facing a strong challenge from far-right populist Geert Wilders.
Analysts believe Erdogan is exploiting the crisis to the full to bring out nationalist votes and ensure victory in the April 16 referendum on the new constitution that opponents fear will create one-man rule in Turkey.
Several top Twitter accounts, including those of a German football club, the French economy ministry and BBC North America, were defaced by pro-Turkey hackers with a message slamming "Nazi Germany" and "Nazi Holland".
"#NaziGermany. #NaziHolland. This is a small #Ottomanslap for you. See you on #April16. I wrote what? Learn Turkish."
The message also featured a swastika and was followed by a video showing extracts of speeches by Erdogan.
According to legend, an Ottoman slap was a barehanded technique used in the Ottoman army that was strong enough to kill an opponent on the spot.
Twitter confirmed the attack. Several nationalist Turkish hacking groups have claimed hacks in recent days but there was no immediate claim for the current mass cyberattack.
"We are aware of an issue affecting a number of account holders this morning," a Twitter spokesperson said, adding the source of the attack had been tracked to a third party application, whose permissions had been removed.
Germany's Borussia Dortmund football club, tennis legend Boris Becker and Amnesty International were also targeted. Turkey has suspended high-level relations with The Netherlands and blocked its ambassador - currently outside the country - from returning to his post.
Many in The Netherlands - a country bombed and occupied by the Nazis in World War II - were hugely offended Erdogan's comment that the country still had "vestiges of the Nazis".
European Union president Donald Tusk said the comparisons were "completely detached from reality.