Thanks to the Los Angeles Times questions are now being asked of Bill's financial dealings with Alibaba, which purchased Yahoo's Chinese operation in a billion-dollar deal in 2005. In September of that year Clinton addressed a conference of Internet big wigs in Hangzhou. Alibaba was already mired in controversy over censorship in China where grave doubts were being raised by human rights groups about the Yahoo! sale. Instead of taking his basic $100,000 to $400,000 speaking fees Bill trousered a still unknown amount from Alibaba for the William J Clinton Foundation, his international charity.

The charity has raised over $500 million since Bill left the White House and has been praised for its involvement in AIDS prevention, medical and poverty relief. But Bill's reliance on the chequebooks of foreign donors and his foundation's refusal to name its donors has caused many to ask awkward questions about the sources and transparency of his money raising.

Others worry about Hillary's promise to use Bill as a roving international ambassador if she makes it to the Oval office.

At a forum in Pennsylvania last night Hillary once again referred to his history of speaking out on human rights abuses in China, but her campaign has dodged questions about Bill's Alibaba links.

Last month the firm's Yahoo China homepage as well as Microsoft's MSN China homepage, carried photographs of Tibetan rioters and a phone number for informants to call.

The New York Times columnist Maureen Dowd wrote yesterday about Clinton's "dubious deals", calling him "a seven-diamond influence peddler" whose actions "do provide an unsavoury contrast with some of the candidate's positions."

Dowd was referring to Bill's $800,000 fee for four speaking engagements promoting a trade deal with Columbia. She might like to add Tibet to her list.