Actress Demi Moore says she is “so grateful” for her former husband Bruce Willis, marking his 69th birthday.

It is the second birthday Die Hard star Willis has celebrated since announcing he had been diagnosed with frontotemporal dementia and stepping away from his acting career.

Willis has five daughters – his three eldest, Rumer, Scout and Tallulah – with Moore, whom he married in 1987.

“Happy birthday, BW! We love you and are so grateful for you,” Ghost actress Moore said on Instagram on Tuesday (US time).

Despite separating in 2000, Moore and Willis have remained friends. He went on to marry actress Emma Heming Willis in 2009, and have daughters Mabel and Evelyn.

“What you might not know, but maybe you could imagine, that being wrapped in his arms is the safest place in this whole wide world,” Heming Willis said in her own tribute on Instagram, accompanied by a shot of Willis with a baby.

“He’s a true gentle-man. With so much love to give and share. That’s what I get to see, his true core. I can tell you, it’s so pure and ever so good.

“Happy birthday, my love. You are the gift that keeps giving.”

The birthday celebrations come days after Willis’s 30-year-old daughter Tallulah publicly spoke about her autism diagnosis for the first time.

The actress posted a video clip taken from the LA premiere of The Whole Ten Yards in 2004, where her father is answering questions on the red carpet, while she is rubbing his shaved head and playing with his ears as he holds her.

“Tell me your (sic) autistic without telling me your (sic) autistic,” she captioned it.

Tallulah said happy birthday to her father on her Instagram story.

Her sister Rumer said: “You are the funniest, most tender, charming, out of this world silly talented and magical papa.

“Looking through these photos this morning I am just filled with the deepest gratitude that we chose to spend this life together.

“I am your first baby and man sometimes I wish I could be tiny enough to just cosy up on your chest again and laugh and cuddle you.

“I love you so deep in my bones I don’t know how my muscles hold them. You are the greatest papa I could ever hope for. Thank you for your generosity, your silliness and heart.”

Scout said she cherished the “affection and the immense freedom with which he’s always loved us”.

“A tender, moody, beautiful, very Piscean man, whose depth of love for his family can only be felt, not articulated,” she said.

“Any words I use would be woefully inadequate. So instead I want to say thank you for loving my papa, thank you for sharing your stories of what he means to you, it’s such a gift to feel your love.”

– AAP