She flashed the giant 33-carat Valentine's ring given to her by her most famous co-star and two-time husband Richard Burton and said: "Oh come on, do I look like I'm dying? Do I look like I have Alzheimer's?"

Just last week reports went around the world that she had little time left and was fast losing her wits. Her most recent pictures showed her in a wheelchair, looking bloated and vague, then came stories that she was bedridden.

But in her first interview in three years, Dame Elizabeth joked, twinkled and revealed a host of secrets in Hollywood on the Larry King live TV chat show for CNN.

She also talked to viewers on a phone-in and modelled some of the jewellery she is launching this week at an exclusive gem fair in Las Vegas. "I'm very busy," she said. "I'm loving what I'm doing, designing jewellery. I do not want to retire."

In a bright, lime-green tunic and wearing a $179,000 (£99,400) sapphire and diamond necklace from her House of Taylor range, she looked radiant at 74. She also showed off an antique diamond necklace given to her by producer Mike Todd, killed in a plane crash in 1958 a year after they married.

Dame Elizabeth admitted she is in chronic pain with a bad back and uses a wheelchair. She occasionally slurred words slightly, probably the legacy of her several strokes and a brain tumour.

She last performed in 2001, in a TV movie called These Old Broads, with Shirley MacLaine. Asked if she would take another acting role, she replied: "If it was really juicy and spicy and challenging." And how about a ninth marriage? "No!" she said firmly, after jokingly asking if King was proposing to her.

She said goodbye to her eighth marriage and seventh husband, toyboy Larry Fortensky, in 1996. Dame Elizabeth revealed that her favourite film was Who's Afraid of Virginia Woolf?, the 1966 dramatic blockbuster in which her explosive performance with Burton at the height of their passion won her an Oscar.

"We both had to pull out all the stops and throw the scenery around. It was fun; it was also cathartic. Then we would go home and cuddle," she said.