Three European scientists shared the 2008 Nobel Prize for medicine for separate discoveries of viruses that cause Aids and cervical cancer, helping doctors fight the deadly diseases.

French researchers Françoise Barré-Sinoussi and Luc Montagnier won for their discovery of human immunodeficiency virus, or HIV.

They shared the award with Germany's Harald zur Hausen, who found human papilloma viruses (HPVs) that cause cervical cancer, the second most common cancer among women.

US researcher Robert Gallo became involved in a dispute with Montagnier in the 1980s over the relative importance of their work in research into HIV and its role in Aids, expressed disappointment at not being included in the prize.

Montagnier, who was in Abidjan, Ivory Coast, at an international Aids conference, said he wished Gallo had shared the prize. "It is certain that he deserved this as much as us two," he said.

Montagnier said he was still optimistic about conquering the disease. The prize, he said, "encourages us all to keep going until we reach the goal at the end of this effort".

Zur Hausen, a German doctor and scientist, receives half of the 10 million kronor (£800,000) prize, and the French share the rest.

Zur Hausen discovered two high-risk types of HPV and made them available to the scientific community, ultimately leading to the development of vaccines protecting against infection.

HPV, transmitted by sexual contact, causes genital warts that sometimes develop into cancer.

"I'm not prepared for this," zur Hausen, 72, of the German Cancer Research Center in Heidelberg, said. "We're drinking a little glass of bubbly right now."

The Montagnier-Gallo row reached such a level in 1987 that then-president Ronald Reagan and Prime Minister Jacques Chirac of France signed an agreement on dividing the enormous royalties from an Aids blood test. In the 1990s, however, the US government acknowledged that France deserved a greater share of the royalties.