European Union leaders are discussing whether to impose sanctions on Turkey over its drilling activities in the Eastern Mediterranean during a two-day summit in Brussels Thursday and Friday, as Turkey voices determination to preserve its rights in the region.

Leaders will decide if the bloc will impose new sanctions on Turkey – a candidate in negotiations to join the EU – or to expand the sanctions list.

"The European Union has to choose between being condemned to a restrictive approach in regional issues with the provocations of Greece and the Greek Cypriot administration or between future-changing possibilities," Parliament Speaker Mustafa Şentop said at a symposium on the role of Parliament in the solution to the Eastern Mediterranean conflict.

"I’d like to hope that no decision that would contribute to the trust crisis between Turkey and the EU will be taken," Şentop said as EU heads of states and governments were preparing to convene in Brussels to patch over internal disagreements to offer a united front in the face of external challenges, including the Eastern Mediterranean dispute.

After chairing a videoconference with EU foreign ministers on Monday, EU foreign policy chief Josep Borrell said that "in several aspects, the situation has worsened," referring to bilateral relations with Turkey and the situation in the Eastern Mediterranean.

The EU on Thursday stated that it will sanction more Turkish individuals and companies responsible for drilling in contested waters in the Eastern Mediterranean, according to a draft statement prepared for EU leaders to agree to at the summit.

The leaders are considering whether to make good on a threat made in October to sanction Turkey over the drilling for hydrocarbons off the coast of Cyprus and off Greece.

Turkish leaders have repeatedly stressed that Ankara is in favor of resolving all outstanding problems in the region through international law, good neighborly relations, dialogue and negotiation. Yet Turkey has also criticized the EU’s stance on the Eastern Mediterranean conflict, calling on the bloc to adopt a fair attitude regarding the dispute and give up on favoring Greece under the pretext of EU solidarity.

"The stakes are very precise, very clear: the credibility of the European Union," Greek Prime Minister Kyriakos Mitsotakis told reporters ahead of the summit.

"So now, it will be seen whether, as Europe, we are really credible in what we ourselves have agreed to," Mitsotakis said.

French President Emmanuel Macron, speaking about Turkey, told reporters upon arrival at the summit that EU countries must defend their sovereignty.

France, Greece, and the Greek Cypriot administration are pushing for strong action against Turkey, but other EU nations including Germany, Italy and Poland oppose imposing broad sanctions or an embargo on a fellow NATO member.

On Wednesday, President Recep Tayyip Erdoğan brushed off the threat of sanctions and accused the EU of acting "dishonestly" and failing to keep its promises.

"Any decision to impose sanctions against Turkey won’t be of great concern to Turkey," Erdoğan told reporters.

Just over a year ago, the EU set up a system for imposing travel bans and asset freezes on people, companies or organizations linked to drilling activities "which have not been authorized by the Greek Cypriot administration, within its territorial sea or in its exclusive economic zone or on its continental shelf."

Efforts by certain EU countries to push sanctions on Turkey amount to "nonsense," a former German MP from the ruling Christian Democratic Union (CDU) said Thursday.

"I think that's nonsense. I think the way we treat Turkey like strict teachers is completely unfair," Jurgen Todenhofer told Anadolu Agency (AA).

Todenhofer urged both the Turkish and German sides to use "softer language."

Greece, with France's support, has disputed Turkey's energy exploration, trying to box in Turkish maritime territory based on small islands near the Turkish coast.

Turkey, which has the longest continental coastline in the Eastern Mediterranean, has rejected the maritime boundary claims of Greece and the Greek Cypriot administration, stressing that these excessive claims violate the sovereign rights of both Turkey and the Turkish Cypriots.

In recent months, Turkey has sent several drillships to explore for energy resources in the Eastern Mediterranean, asserting its own rights in the region, as well as those of the Turkish Republic of Northern Cyprus (TRNC).

Şentop also said Thursday that a solution to the Eastern Mediterranean conflict can only be ensured through equal sharing of resources, underlining during a symposium that Turkey keeps the door to dialogue open.

"Disagreements on territorial waters, the disarmament of the islands and airspace in the Aegean are also part of the Eastern Mediterranean problem," Şentop pointed out.

Şentop said that although all these problems originate from the sharing of energy resources, they are also linked to a greater struggle for influence in countries such as Syria, Libya and Lebanon.

"We cannot explain Turkey’s presence in the Eastern Mediterranean solely in terms of strategic resources and legitimate rights. Turkey is also there to ensure a fair sharing on the basis of peace," he added.

With the aim of decreasing tensions in the region, Ankara and Athens have been holding NATO-led deconfliction talks, but the latter has been keeping all channels of dialogue closed.

Turkey’s Oruç Reis survey vessel returned to the southern port of Antalya from Mediterranean waters after having completed its seismic research activities on Nov. 30. Ankara also withdrew the Oruç Reis from contested waters ahead of a previous EU summit in October to allow for diplomatic talks.