Kylie Minogue has told of the hurt caused to her sister Dannii after Simon Cowell's biography revealed that she had a fling with the TV and music mogul.
The brief, past relationship came to light just weeks after Dannii, 40, announced in April that she was separating from partner Kris Smith, the father of her young son Ethan.
Minogue, 44, told Glamour magazine "my sister is going through a really difficult time" adding of the revelation: "It was a bit of a second blow after 'Oh, my relationship has broken down.'"
Asked whether she thought that X Factor boss Cowell had betrayed her sister, a former judge on the TV show, by talking to biographer Tom Bower, she said: "Well, he doesn't need to do any of those things. Or maybe he does... who knows? I don't know the guy."
Minogue said that her younger sister, who is in Australia, was "being pragmatic" since the split with her partner of four years.
"She and Kris have been amicable, and after heartbreak and disappointment, then it's just organisation, concentrating on Ethan," she said.
"We just have normal sister chats when we can - and that's all you need to know, that your sister's there. If she called me and said, 'I'm really flipping out, I need to see you,' I'd be on a plane tonight.
"But Dannii is tough... Dannii will be all right. Of course she'll be all right," she told the magazine.
Her comments come after Cowell, who co-operated with the writer of his unofficial biography, apologised to anyone who might have been embarrassed by the book, Sweet Revenge.
"I want to publicly apologise to anybody I embarrassed because I have tried to keep my private life quiet a bit and I do have to apologise to certain people and certain members of my family," he said.