Internationally acclaimed novelist Khaled Hosseini has said he was a proud father after revealing that his daughter had come out as transgender.

Hosseini, whose debut novel 'The Kite Runner' was a bestseller with millions of copies sold worldwide, took to social media to share the news.

"Yesterday, my daughter Haris came out as transgender," wrote the Afghan-American writer on his Facebook.

"I have known about Haris’ journey since last year and I’ve watched her navigate some very trying personal times. Transitioning is such a complicated undertaking—emotionally, physically, socially, psychologically—but Haris has met each challenge with grace, patience, and wisdom."

Hosseini, who is a goodwill ambassador for the United Nations High Commissioner for Refugees, said he was a proud father.

"As a father, I have never been prouder of her. I am delighted to now have not one but two beautiful daughters."

Hosseini lauded his daughter's courage and said her journey has taught him a lot. "I am inspired by Haris’ fearlessness, her courage to share with the world her true self. She has taught me and our family so much about bravery, about truth. About what it means to live authentically.

"I know this process was painful for her, fraught with grief and anxiety. She is sober to the cruelty trans people are subjected to daily. But she is strong and undaunted.

"I love my daughter. I will be by her side every step of the way, as will our family. We stand behind her. It’s a privilege to watch her enter the world as the beautiful, wise, and brilliant woman that she is. May God bless her."