French military instructors training soldiers in Ukraine would be a "legitimate target" for Russian strikes, Moscow's top diplomat said Tuesday, amid reports France could send trainers to the country.

France does not officially have military personnel assisting or training Ukrainian forces in Ukraine at the moment, but Kyiv said last week it was "in talks" with Paris on the issue.

"Whoever they are labeled as, whether they are members of the French armed forces or are just mercenaries, they represent an absolutely legitimate target for our armed forces," Russian Foreign Minister Sergei Lavrov told a news conference.

The Kremlin similarly did not rule out strikes on foreign instructors in Ukraine when asked about the issue earlier on Tuesday.

"Any instructors who are engaged in training the Ukrainian regime do not have any immunity. It does not matter whether they are French or not," Kremlin spokesman Dmitry Peskov told reporters in a briefing.

Ukrainian army chief Oleksandr Syrsky said last week French military instructors would soon arrive in the country, a claim that was quickly walked back by Ukraine's defence ministry.

French President Emmanuel Macron has refused to rule out deploying troops to Ukraine, despite reluctance from other NATO members and furious condemnation from Moscow.

Russia has warned against such a move, arguing it would dramatically escalate the conflict.

It has repeatedly vowed to destroy Western military hardware sent to the country.