Canadian singer Loreena McKennitt is seeking to prevent details of her private life appearing in a book by former friend Niema Ash called "Travels With Loreena McKennitt."

McKennitt won a High Court ruling in London last year in which the judge prevented the disclosure of details including passages about personal relationships, emotional vulnerability and her feelings for her late fiance who drowned.

But Ash and the book's publishers, Purple Inc Press, are seeking to overturn the ruling, arguing that it struck a blow to freedom of expression.

David Price, lawyer for Ash and Purple, told the court that considerable uncertainty surrounded privacy laws in the country.

"There is a perception that the law relating to breach of confidence and misuse of private information is in a state of some uncertainty," he said. "This uncertainty is undesirable. It has a chilling effect on freedom of expression."

The McKennitt case also ended this week and judgment is awaited. Two cases in 2004 favored celebrities over the media.

The law lords decided supermodel Naomi Campbell's rights were breached when a newspaper ran a story saying, correctly, that she had visited Narcotics Anonymous.

And the European Court of Human Rights condemned Germany for failing to stop press photos of Princess Caroline of Monaco which it said violated her right to respect for private life.