On April 17, a joint report by Parliamentary Assembly of the Council of Europe (PACE) and Organization for Security and Cooperation in Europe (OSCE) election observers claimed that an “unlevel playing field" had characterized the weekend referendum, but Turkish officials have blasted the conclusions as “biased”.

However, it was not the first time that the OSCE's observers have been accused of filing partial reports during elections, according to data an Anadolu Agency correspondent compiled.

Belarus closed down OSCE office in Minsk after 2010 presidential elections, during which the observers said the country was holding an undemocratic vote.

The Belarusian government accused OSCE observers of spying and said they had collected intelligence to redesign the country.

Ricardas Ramoska, the former 2nd secretary at the Lithuanian embassy in Belarus, was one of the OSCE's observers in Turkish referendum and according to a report, he was charged with bribery in his country.

He was convicted of accepting a bribe to issue an entrance visa to Lithuania.

In 2007, Benjamin Moreau, a member of OSCE Center in Turkmenistan's capital Ashgabat, made headlines after the country's officials said Moreau was helping citizens accused of plotting against the state.

Turkey’s foreign minister Tuesday slammed the objectivity of a European observer of the weekend referendum, citing a photo of the German MP holding up a flag of the terrorist PKK.

"German MP Andrej Hunko posing with symbol of PKK terrorist organization is the election observer of PACE," Mevlut Cavusoglu said on Twitter. "How can one expect objectivity?" he wrote.

Hunko, however, said the photograph was taken in Cologne in October 2014, during a rally which he said was not an expression of sympathy with the PKK.

Another German MP Heike Haensel, who is known to have attended several pro-PKK activities that demanded the removal of PKK from terror list, was among the international team that observed the referendum.

Danish MP Nikolaj Villumsen, who served on the PACE observation team and belongs to the left-wing Enhedslisten party, helped raise money for the YPG, the terrorist PKK’s Syrian branch, with the party donating some $8,000 to the YPG, Danish daily Jyllands-Posten reported in March 2014.

The PKK, the YPG’s parent organization, has been listed as a terrorist organization by Turkey, the U.S. and the EU.

More than 1,200 people, including security personnel and civilians, have lost their lives since the PKK resumed its decades-old armed campaign in July 2015.

On April 6, Villumsen and Pernille Skipper, another Enhedslisten MP, posted a video on Villumsen's Facebook account urging Turkish citizens living in Denmark to cast No votes.

Ana Miranda, another observer, posted a photo on her Twitter account on Monday and wrote: "On our way to electoral observation #Kurdistan. Women team @HeikeHaensel @dieLinke @lorenalacalleA @ealkartasuna & me @obloque @EUPARTYEFA," while she was in southeastern Diyarbakir province.

The report was issued after the Yes votes unofficially won with 51.41 percent, while the No votes stood at 48.59 percent.

Anadolu Agency