Türkiye expressed concern about Russia's attempts to hold referenda in occupied regions in Ukraine, the Foreign Ministry said Wednesday.

Referring to the referenda as "illegal fait accompli," the ministry said such attempts will not be recognized by the international community.

"On the contrary, they will complicate efforts to revive the diplomatic process and will further deepen instability," the ministry said.

Foreign Minister Mevlüt Çavuşoğlu said Tuesday that the decision by Russia to announce referendums shows "the seriousness of the situation" in Ukraine.

"Recent Russian decision on partial mobilization and the announcement of annexation referenda in Luhansk, Donetsk, Herson and Zaporijia demonstrate the seriousness of the situation," Çavuşoğlu said while co-chairing the 12th Ministerial Meeting of the U.N. Groups of Friends of Mediation on the sidelines of 77th session of U.N. General Assembly in New York.

The top diplomat said there is a need for a more proactive approach to diplomacy and mediation.

"This is why we selected, ‘Avoiding Humanitarian Crises Through Mediation,' as the theme of our meeting today," he said in opening remarks. "That's what we try to do through our engagement with Ukraine and Russia."

Çavuşoğlu warned that the longer the war continues, the more difficult it is to reach a "just and mutually acceptable" solution.

He stressed that dialogue and diplomacy are the only way out of the seven-month conflict.

In September, Ankara also rejected the parliamentary elections held in Crimea, which Russia illegally annexed from Ukraine in 2014, underlining the country's support for Ukraine's territorial integrity.

Spanish Prime Minister Pedro Sanchez also "categorically condemned" the referenda planned in occupied areas of Ukraine.

Earlier in the day, Putin announced a partial mobilization of around 300,000 Russians with military experience to fight in Ukraine and alluded to using nuclear weapons to protect Russia from Western aggression.

"We know we are now in a more critical phase of the war, in which the aggressor realizes he's losing," Sanchez said in New York at a forum for Latin America, Spain and the U.S.

He said the referenda in Russian-occupied parts of Ukraine represent "a new violation of international law."

"The international community will never recognize the results of the referendums," he added.