His comments came as France was hosting a summit of European leaders and Ukraine's President Volodymyr Zelensky to boost Ukrainian security ahead of a potential ceasefire with Russia.

Croatian Prime Minister Andrej Plenkovic attended the meeting, which is seeking to set out what security guarantees Europe can offer, including the possible deployment of military forces by a so-called "coalition of the willing".

"A Croatian soldier will not go to Ukraine under any arrangement, that is completely out of the question," Milanovic, who won a second term by a landslide in January, said on Facebook.

"The Croatian Army will not go on a mission, and one of the reasons is that this mission will never happen, with or without Croatia, because the elementary conditions for this mission have not been met -- a peace agreement and the consent of the other party, which is unfortunately Russia," he added.

Milanovic has been a frequent critic of the military aid and Croatia's plans to help train Ukrainian troops.

As a NATO and EU member, Croatia has donated hundreds of millions of euros in aid to help Ukraine's fight against Russia's invasion, including military helicopters.

Despite having limited powers, the president serves as the supreme commander of Croatia's armed forces and has a say in its foreign policy.

Milanovic's political opponents have frequently accused him of holding "pro-Russian" views and undermining Croatia's credibility in NATO and the EU.

But Milanovic, the most popular politician in the country of 3.8 million people according to surveys, repeatedly argued that his main task was protecting Croatia's interests.