World number one Roger Federer has donated a signed shirt while stars like Justine Henin, Maria Sharapova and Rafael Nadal have put signed rackets up for auction to help pay for treatment for Austrian doubles players Sandra and Daniela Klemenschits, according to the WTA Tour website, which organised the auction.

The 24-year-old sisters, who were ranked in the doubles top 100 in 2005 and competed in tournaments as recently as last year, were diagnosed in January with a rare kind of cancer in the lower abdomen.

They recently checked into a clinic in Igls, near Innsbruck, that costs 10,000 euros (13,500 dollars) per week for the two of them, their physiotherapist and personal friend Kurt Waltl told AFP Friday.

The twins are expected to spend another eight weeks in the clinic, he added.