RIO DE JANEIRO, April 15, 2008 (AFP) - Health authorities in Brazil have rejected an offer by Naomi Campbell to donate blood to help with a dengue fever outbreak in the country because the British supermodel was recently operated on.

Michel Klein 2007/2008 advertising campaign with Naomi Campbel

"Unfortunately I can't give blood for Rio de Janeiro, but I'll surely be back," she told reporters Tuesday after being turned away from the HemoRio medical center.

Campbell, 37, underwent surgery in Brazil in February to remove a cyst.

She is a regular visitor to the country, having spent carnival in the northern city of Salvador and visiting wealthy friends.

Blood transfusion rules in Brazil exclude patients who have been operated on in the preceding six months, doctor Esther Lopes of HemoRio explained.

Rio de Janeiro has been suffering from dengue since the beginning of the year.

At least 83 people in the state have died from the moquito-borne tropical disease, 51 of them in the city of Rio. A total of 75,000 have been infected.

Campbell said she saw Rio's problems with the outbreak in London and decided to fly over to help.