Betty White died "peacefully in her sleep". 

The Golden Girls star passed away on New Year's Eve aged 99 and her agent has slammed online claims her passing was related to her having had a coronavirus booster vaccine just a few days before, insisting that's not the case and her death was due to natural causes. 

Her long-time friend and agent, Jeff Witjas, told NBC News: "[Betty] died peacefully in her sleep at her home. 

"People are saying her death was related to getting a booster shot three days earlier but that is not true. She died of natural causes. Her death should not be politicised —that is not the life she lived." 

A quote circulating online attributed to Betty from 28 December has also been dismissed as false by Jeff. 

The screen legend has been reported to have said last week: "Eat healthy and get all your vaccines. I just got boosted today." 

However, her agent insisted: "Betty never said this". 

Jeff confirmed his late client hadn't received a booster that day, but he didn't comment as to whether she had received one at all. 

Following the passing of the 'Proposal' star, Jeff admitted she had always been more to him than just a client. 

He explained: "She was an incredible lady. Hard to put into words. We had a special relationship, far more than just a client." 

Actress Betty White passed away on New Year's Eve aged 99. Photo / AP 

Jeff believed it was important to keep reminding Betty of her popularity around the world. 

He shared: "She knew it, but I would tell her often. Even when she wasn't working, I said, 'Betty, millions of people out there are still asking for you. You're getting your fan letters; I'm getting offers for you.' 

"I don't know if she ever embraced it, [or] really, really felt it. The extent of it. I really don't. 

"I would always reinforce it with her because I always felt she should know that. I never wanted her to think while she was sitting at home, that the world has passed her by. It never did." 

He added that her popularity went "beyond love". 

He said: "Betty lived a great life and she lived a life that she chose. She was happy. 

"Every time I told her, 'Betty, you're loved,' she would look at me with a wry smile and say, 'Really?' I hope she knew. I think she did. It was something beyond love."