PARIS (AFP) - A French volunteer fighter in Ukraine has been killed in combat, Paris confirmed on Friday (June 3), following reports that the man died in artillery fire in the Kharkiv region.

"We are aware of the sad news that a French citizen has been fatally wounded during combat in Ukraine," a foreign ministry spokesman said.

"We remind everyone that the whole of Ukraine is a war zone. In this regard, travel to Ukraine is formally advised against, for whatever reason."

The Europe 1 radio station reported on Thursday that the young man had joined a foreign defence unit in Ukraine and was fighting around Kharkiv, a north-eastern city which has been shelled heavily by Russian forces but remains in Ukrainian hands.

Many foreign fighters have responded to Ukrainian President Volodymyr Zelensky's appeal for volunteers to come and repel invading Russian forces.

The Ukrainian government put their number at around 20,000 in March, though the figure has not been independently verified.

The death was the first time a French fighter has been killed in the war, Europe 1 reported.

In late April, the British government confirmed that one of its citizens, identified in the media as a 36-year-old army veteran, had been killed in Ukraine, and another was missing.