Sharon Osbourne has revealed U.S. President Donald Trump left her a heartfelt voicemail message following the death of Ozzy Osbourne.

The Black Sabbath frontman died at the age of 76 on 22 July, just 17 days after he appeared onstage for the Back to the Beginning farewell concert held at Villa Park in his native Birmingham, England.

In the latest episode of her family's podcast The Osbournes, Sharon played a voicemail recording left for her by Donald in the days after Ozzy's passing.

"Hi, Sharon. It's Donald Trump, and I just wanted to wish you the best and the family," the American leader said in the message. "Ozzy was amazing. He was an amazing guy. I met him a few times and I wanna tell you he was unique in every way and talented. So, I just wanted to wish you the best, and it's a tough thing, I know how close you were, and whatever I can do. Take care of yourself, say hello to the family. Thanks, bye."

Sharon, 73, knew Donald from his time appearing on The Celebrity Apprentice, which she competed in back in 2010.

The reality TV star went on to insist that she felt it was important to put politics aside at this time and emphasised that she had always found the 79-year-old kind to her.

"All I know is a man that I know, I worked with for a month. I spent one month with him and his wife (Melania Trump), who was always gracious, elegant, just a delight to talk to, his wife. And he was always, 'How are the children? How is Kelly? I'm so proud of Kelly and Jack for what they've done, and their manners are great,'" she commented, before tearing up. "And he was just a great guy to talk to and he has always treated me with respect... The thing is all I know is he has treated me with respect, your father with respect. He wanted nothing from us. Nothing. Melania, the same, nothing. And they have been great. And for him to take his time to do that for us."

In response, Sharon and Ozzy's son, Jack Osbourne, conceded: "Love him or hate him, he didn't have to call and leave a voicemail."

Elsewhere in the episode, Jack shared that the family also received a letter from King Charles III in which he offered the family his condolences.

"Our King, now we're talking!" Sharon praised of the British monarch. "Our King is an amazing person. He is an amazing person, not just because he wrote to us when Ozzy passed, but if he did it for us, you know he does it for many, many, many people. Now here's a man that does know what's going on in the street with people. Not just politics, not just, you know, here's a man that cares about the environment, animals. He cares about many, many, many things. And he's got a good heart. He's got a good heart."