Terras, who retired as head of the Estonian Defense Forces (EDF) last December, echoed the stance of European People's Party (EPP) prospective leader Manfred Weber, following discussions the two men had in Vilnius, Lithuania last Thursday, BNS reports.

Isamaa's outgoing MEP, Tunne Kelam, sits with the EPP group at the European Parliament – under EU regulations all elected MEPs, including independents, must sit with one of several groups.

The EPP rationale is that, since the EU is based on Christian values, no nation which calls these values into question or may obscure them, should be considered for membership, it is reported.

The majority of Turkey's population are at least nominal adherents to Sunni Islam, though under the country's secular constitution, whose origins date back the founding of the republic under Mustafa Kemal Atatürk in the early 1920s, there is no official state religion, and religious freedoms are guaranteed in its constitution.

Good for NATO but not EU

"For Europe, Turkey is a good partner and an important ally in NATO, but we have no real common ground when it comes to the prospect of the EU,'' Terras said on the matter, BNS reports.

''Turkey should not be reckoned with as a potential candidate country in the future, and that should be stated clearly and the negotiations ended," Terras continued. Other, less fundamental opposition to Turkey's EU membership has come from other quarters, given the perception of the authoritarian nature of President Recep Tayyip Erdoğan's regime.

Manfred Weber reiterated the comments in a speech in Munster, Germany, on Saturday, BNS reports.

"We are proud that this continent has a Christian influence ... this is not only something for museums, and it should guide us in the future," Weber said.

Such values would entail Europeans being "frank" in their discussions with Ankara, "which is why I believe that Turkey cannot be a member of the EU", Weber continued.

The European elections in Estonia are held on May 26.