Francis Ngannou said late Monday that his 15-month-old son Kobe had died.

The French-Cameroonian boxer and former MMA fighter posted on social media platform X: "Too soon to leave but yet he's gone.

"My little boy, my mate, my partner Kobe was full of life and joy.

"Now, he's laying without life. I shouted his name over and over but he's not responding.

"I was my best self next to him and now I have no clue of who I am. Life is so unfair to hit us where it hurts the most," Ngannou added.

Ngannou was knocked out by Anthony Joshua in Saudi Arabia last month, his second heavyweight defeat since switching from MMA.

Ngannou had pushed world champion Tyson Fury during a controversial points defeat in his first professional boxing match in Saudi Arabia last October.

A few hours before revealing Kobe's death, Ngannou had posted on X, without reference to his son: "What's the purpose of life if what we're fighting tooth and nail to get away from is what finally hit us the hardest?

"Why is life so unfair and merciless?"

The fight world reacted with messages of condolence.

"I am so sorry to hear of your loss Francis, my prayers are with you and your family at this time," wrote fellow UFC fighter Conor McGregor on X.

The fighter's manager, Marquel Martin, posted: "Please respect @francis_ngannou and his family during this traumatic time. I along with millions (of) others will be praying for their strength."

Veteran ring announcer Michael Buffer said on social media: "The entire world of sports and beyond stand crushed and painfully supportive with Francis at this time.

"Please know that millions of us embrace little Kobe with our prayers."