Al Pacino was "shaken" by the passing of his The Godfather co-star Diane Keaton

Pacino, who had an on-and-off romance with The First Wives Club actress from 1974 to 1990, told Deadline: "I am deeply saddened by Diane Keaton's passing.

"When I first heard the news, I was shaken. Diane was my partner, my friend, someone who brought me happiness and on more than one occasion influenced the direction of my life.

"Though over 30 years have passed since we were together, the memories remain vivid, and with her passing, they have returned with a force that is both painful and moving."

The Carlito's Way star reflected on how Keaton was wonderful both as an actor and a person.

Pacino said: "She lived without limits, and everything she touched carried her unmistakable energy. She opened doors for others, inspired generations and embodied a once-in-a-lifetime gift that radiated through her work and her life.

"On screen, she was magnetic - lightning and charm, hurricanes and tenderness. She was a wonder. Acting was her art, but it was only one of the many ways she expressed her imagination and creativity.

"People will miss her, but more than that, they will remember her. She left a mark that cannot fade. She was unstoppable, resilient and above all, deeply human.

"I will always remember her. She could fly - and in my heart, she always will."

Tributes to the Annie Hall star have flooded in from Hollywood luminaries since her death with Woody Allen - who dated the Oscar-winning actress in the early 1970s and made eight movies with her - recalling how he fell for her as soon they first worked together on his Broadway production of Play It Again, Sam.

In a lengthy tribute published on The Free Press, the 89-year-old filmmaker wrote: "Unlike anyone the planet has experienced or is unlikely to ever see again, her face and laugh illuminated any space she entered.

"I first laid eyes on her lanky beauty at an audition and thought, If Huckleberry Finn was a gorgeous young woman, he'd be Keaton...

"For the first week of rehearsal we never spoke a word to one another. She was shy, I was shy, and with two shy people things can get pretty dull. Finally, by chance we took a break at the same moment and wound up sharing a fast bite at some Eighth Avenue joint.

"That was our first moment of personal contact. The upshot is that she was so charming, so beautiful, so magical, that I questioned my sanity. I thought: 'Could I be in love so quickly?'"