International tennis chiefs insisted Wednesday that "political statements" are not banned at Grand Slam events after Novak Djokovic controversially wrote "Kosovo is the heart of Serbia" on a camera at the French Open.

Djokovic defended his message in comments to Serb media, saying that Kosovo is Serbia's "cradle, our stronghold".

The International Tennis Federation (ITF), the governing body of the sport, said they had received a request from the Kosovo Tennis Federation demanding Djokovic be sanctioned over his actions.

However, they pointed out that such statements do not contravene regulations.

"Rules for player conduct at a Grand Slam event are governed by the Grand Slam rulebook, administered by the relevant organiser and regulator. There is no provision in this that prohibits political statements," an ITF spokesman told AFP.

Djokovic was criticised earlier Wednesday for his comments about recent clashes in Kosovo by French sports minister Amelie Oudea-Castera who said he "shouldn't get involved".

Ukrainian player Elina Svitolina said Djokovic should be free to "say his opinion".

Svitolina, who has repeatedly spoken out over tennis' response to Russia's invasion of Ukraine, believes players should be able to talk publicly about political issues.

"We are living in the free world, so why not say your opinion on something?," said Svitolina, who reached the third round with a 2-6, 6-3, 6-1 win over Storm Hunter on Wednesday.

"I feel like if you stand for something, you think that this is the way, you should say.

"I mean, if you are with a friend sitting, talking, you're going to say your opinion, he is going to say his opinion. So why not?"

Thirty peacekeepers from a NATO-led force in Kosovo were injured in clashes with ethnic Serb demonstrators on Monday during protests about the installation of ethnic Albanian mayors in northern Kosovo.

Kosovo, mostly populated by Muslim ethnic Albanians, broke away from the then-Yugoslavia in the late 1990s and declared independence in 2008, in a move that has never been accepted by neighbouring Christian-majority Serbia or its ally Russia.

"For me it's just part of human life, politics, sports, you know, different things," added Svitolina.

The former world number three only recently returned from maternity leave having also taken a break following Russia's invasion.

"I just try to think about the fighting spirit that all of us Ukrainians have and how Ukrainians are fighting for their values, for their freedom in Ukraine," she said.

"And me, I'm fighting here on my own front line."

Svitolina will next face either Caroline Garcia or Russian Anna Blinkova in the third round, while Djokovic plays Marton Fucsovics in round two in Wednesday's night session.