Orange Prize-winning author Lionel Shriver has condemned British TV for patronising its audience and broadcasting an endless diet of property and weight loss programmes and cruel gameshows.

The best-selling writer behind We Need to Talk About Kevin said BBC1 and BBC2, ITV, Channel 4 and Five were all guilty of underestimating viewers.

Shriver, who won the Orange Prize in 2005, said the public "deserve better than How to Look Good Naked and How Clean Is Your House?".

The American-born author of eight novels said programmes had deteriorated dramatically since she moved to Britain 20 years ago.

Shriver, 50, condemned gameshows that "create cruelty and humiliation", endless "reruns of Friends", "weight loss" programmes, a "lunatic profusion of British property shows" and "the worst of American exports".

Speaking at the Edinburgh International Television Festival, Shriver said: "It used to be that the contrast between engaging British television and the trash on American TV was shocking. Now the similarity is shocking.

"The biggest mistake contemporary television makes is to patronise the viewers.

"Your viewers are smarter, more sophisticated, and more hungry for real information than you might think."

She continued: "When I was raised in the US I was brought up to revere British TV. I long associated British TV with quality.

"I have lived in the UK for 20 years and during that time I have seen that quality deteriorate."

* Panorama reporter John Sweeney yesterday told the festival that the BBC should axe one of its digital channels - BBC3 or BBC4 - instead of making further cuts to its current affairs budget.

Together, BBC3 and BBC4, cost about £190m a year, making them some of the most expensive BBC channels to run on a cost-per-viewer basis.

Mr Sweeney said: "It would be better to close down BBC3 or BBC4 than cut current affairs again. Stop cutting current affairs - it is bad for the soul".

He added that BBC TV current affairs was already "a pale shadow" of its former self.

His comments came after BBC Chairman Sir Michael Lyons said "radical changes" could be imposed when the trust ruled on cost-saving plans this autumn, following the lower-than-expected licence fee settlement.