A poster of Turkish President Recep Tayyip Erdogan on a building in central Istanbul's Taksim Square on March 14, 2017. (Lefteris Pitarakis/AP)

Hackers apparently sympathetic to the Turkish government posted Twitter messages Wednesday on hundreds of public accounts deriding Germany and the Netherlands as Nazis, opening a new front in an escalating war of words between Turkey and its European allies.

It was not clear who was responsible for the tweets, which were posted on the accounts of Amnesty International, UNICEF and the BBC, among others. But the messages suggested backing for Turkish views — echoing recent rhetoric by Turkish President Recep Tayyip Erdogan.

Erdogan has accused Germany and the Netherlands of “Nazism” after officials in those countries prevented Turkish ministers from holding political campaign events to court expatriate Turks.

Twitter said it had revoked access to a “third-party app” in response to the messages, which were mostly removed by late Wednesday, the Associated Press reported. Twitter Counter, an analytics company monitoring the social media site, said it had started an investigation into the hack, the AP reported. 

This is a screen grab of the Amnesty International Twitter feed taken on March 15. Twitter says it has revoked access to block "a third-party app" apparently used to hack a number of accounts to broadcast pro-Turkish messages, like the one illustrated. (AP)

Turkey is weeks away from a referendum that could shift its system of government and grant Erdogan broad new presidential powers while extending his tenure in office. With polls showing an evenly divided electorate, Erdogan’s supporters have been anxious to sway millions of Turkish voters living in Europe. 

That desire has collided with rising anti-Erdogan sentiment in several European countries, stemming from his government’s crackdown on dissidents and the surging popularity in Europe of anti-immigrant parties.

In the Netherlands, voters cast ballots Wednesday in elections that mark a test of strength for the country’s anti-Islam forces, led by Geert Wilders, who wants to ban the Koran and shut down mosques.

After more than half a dozen Turkish campaign rallies in the Netherlands and Germany were canceled, Turkish officials accused the Dutch and German governments of caving to domestic nationalist fervor.

At the same time, Erdogan’s increasingly scathing responses are broadly seen as his own attempt to whip up nationalist support ahead of the referendum. The broadsides by Erdogan include blaming the Netherlands for the 1995 massacre in Srebrenica, Bosnia, which was, in fact, carried out by Bosnian Serb forces. Dutch peacekeepers had been assigned to the area.

It remained to be seen whether his approach — which risked long-term damage to Turkey’s relationship with Europe — would have an immediate effect on the Turkish referendum.

Ozer Sencar, chairman of the polling company MetroPOLL, said that anti-Europe appeals were unlikely to sway the portion of the electorate that was still undecided, saying those voters were likely to be more concerned with Turkey’s faltering economy than a political dispute with European countries.  

The latest unemployment figures, released Wednesday, did not seem to provide any relief for the Turkish government. In December, the unemployment rate hit 12.7 percent, the highest rate in seven years, according to data released by the Turkish Statistical Institute.