The criticism comes as the monitoring group held a meeting with the country's Supreme Election Council to present its preliminary report.
“How can one expect objectivity,” Turkish Foreign Minister Mevlut Cavusoglu sent in a tweet on Tuesday, showing German MP Andrej Hunko holding a red PKK flag at what Hunko says was a free-speech event in Cologne, Germany in 2014.
It is unclear when Turkish officials became aware of Hunko’s photo with the PKK flag.
He had visited the country at least on one more occasion in 2014 when he and other European MPs monitored the then local elections across the country.
Hunko, a member of the left-wing ‘Die Linke’ party, is also a member of Parliamentary Assembly of the Council of Europe (PACE) which accompanied a delegation from the European Organization for Security and Co-Operation.
The OSCE visited the country to observe and assess the Turkish referendum at the request of Turkey, the organization says on its webiste.
Hunko claimed that PACE does not consider the PKK a terrorist organization.
“As a former member of the Parliamentary Assembly of the Council of Europe, he [Cavusoglu] is aware that it does not classify the PKK as a terrorist organization,” Hunko’s official website said.
The Commissioner of Human Rights from the Council of Europe, and its European Court of Human Rights had called the PKK a terrorist organization in previous cases.
The OSCE also says that it works with international organizations to fight terrorism and is guided by the UN Global Counter-Terrorism Strategy. It says its member states, including Turkey, have the right to fight terrorism so long as it adheres to proportionality and respect the international standars of human rights.
“Respect for human rights has deteriorated at an alarming speed in recent months in the context of Turkey’s fight against terrorism” said Nils Muižnieks, the Council of Europe Commissioner for Human Rights in April 2016.
Hunko said in his statement that he did not necessarily hold the flag to support the PKK, claiming that it was in protest against a German ban on Kurdish symbols, including the PKK's.
The PKK is a named terrorist organization by the European Union — to which Germany is a member — the US and Turkey.
“The objective is transparent: They want to discredit my observations of the controversial vote and distract from the fact the referendum took place on April 16 under undemocratic and unfair conditions,” Hunko’s website read.
Hunko added that he and an Austrian colleague observed the referendum voting “in Diyarbakir, in the middle of the Kurdish regions, as well as in Mardin.”
European poll observers met Tuesday to give Turkey’s top election authority, the Turkey’s Supreme Board of Elections (YSK), the group’s preliminary report.
“We discussed the contents of the report,” Tana de Zulueta, head of the OSCE observation mission, told reporters.
On Monday, the OSCE claimed that a “lack of equal opportunities, one-sided media coverage and limitations on fundamental freedoms” had created an “unlevel playing field” in the constitutional referendum.
Turkey’s President Recep Tayyip Erdogan and the Foreign Ministry have dismissed the criticisms as “unacceptable” and the report as “biased.”
The OSCE’s final report on the referendum will be released in approximately eight weeks.
“I thank the Supreme Board of Elections for all the assistance it gave during our presence in the country,” Zulueta added.
Kemal Kilicdaroglu, the general chairman of the (CHP) said that it was rejecting the outcome of the referendum on the basis of the High Election Board (YSK) accepting ballots from unstamped envelops.
"The YSK hearsay is feeding itself," the CHP tweeted, adding that if the CHP had all the facilities available to it as the state had, the 'Yes' vote would not have prevailed.
On Sunday, a majority of Turkish voters cast ballots in favor of 18 constitutional amendments set to, among other things, switch Turkey from a parliamentary system of government to a presidential one.
