Mrs Palin, Mr McCain's running mate in their unsuccessful White House campaign, told CNN the allegation 'is not true'. She said the leaks could have come from people who helped her with preparation for her debate against Democratic vice-presidential candidate Joe Biden.

She said she remembered having conversations during debate preparation about Africa and the North American Free Trade Agreement (Nafta).

A Fox News report cited unidentified campaign sources who said Mrs Palin did not know Africa was a continent and could not name the three countries in Nafta - the United States, Canada and Mexico.

'I think if there are allegations based on questions or comments that I made in debate prep about Nafta or about the continent versus the country when we talk about Africa there, then those were taken out of context, and that is cruel and mean-spirited, it's immature, it's unprofessional, and those guys are jerks,' Mrs Palin said.

It's not fair and it's not right,' she said.

She also described accusations that she spent exorbitant amounts of money on clothes for the campaign as 'sexist'. -- REUTERS