The full implementation of the Minsk agreement is key to realizing lasting peace in Ukraine's eastern regions, Ukrainian President Petro Poroshenko said Wednesday.

Poroshenko made the remarks during a meeting with Ukrainian representatives in the international working group on normalizing the situation in eastern Ukraine prior to a new round of peace talks on the Ukrainian crisis in the Belarusian capital of Minsk.

"Any amendments, shift of the format or departure from the provisions of the Minsk deal are unacceptable," Poroshenko was quoted as saying by his press service.

Poroshenko stressed the importance of implementing the Minsk peace agreement step by step and strictly adhering to the prescribed plan on resolving the conflict.

"The first key task is to ensure a comprehensive cease-fire, which must be verified and confirmed by the representatives of the Organization for Security and Cooperation in Europe (OSCE)," Poroshenko said.

He also underlined the importance of completing the withdrawal of heavy weaponry from the front line, releasing all hostages from both conflicting sides and preparing local elections in Donetsk and Lugansk.

In addition, Poroshenko has urged the representatives of the working group to intensify their efforts to resolve the humanitarian crisis in the conflict-hit areas and speed up economic recovery in the regions.

Later in the day, representatives from Ukraine, Russia and the OSCE will hold talks in Minsk to explore political ways out of the conflict in eastern Ukraine, which has claimed over 6,100 lives.