Fico, commenting on the planned meeting between Trump and Putin in Alaska on Friday, said that regardless of what the two agree on, Ukraine will suffer the most.

"Remember the ancient African truth that I like to repeat so much? Whether elephants fight or have sex, the grass always suffers. No matter how the elephant talks end on August 15, the grass will suffer - in this case, Ukraine," said the Slovak prime minister, who is known for his Moscow-friendly stance.

The Ukrainian Foreign Ministry has called Fico's statement regrettable.

"It is regrettable that the head of government of a European Union member state allows openly offensive rhetoric towards Ukraine and the Ukrainian people, who are heroically fighting against Russian aggression every day, containing it on their land in the interests of the security of all of Europe," the Ukrainian Foreign Ministry said in a statement.