The Israeli prime minister, Ariel Sharon, is undergoing surgery after suffering a "significant" stroke, doctors in Jerusalem said tonight.
Officials said Mr Sharon had suffered cerebral bleeding and was unconscious in hospital. The Israeli prime minister's authorities have been transferred to his deputy Ehud Olmert.
Mr Sharon's personal doctor, Shlomo Segev, said the prime minister was in surgery and that the operation would take several hours. Mr Sharon, 77, was taken to Hadassah hospital from his ranch in the Negev desert.
Dr Shlomo Mor-Yosef, director of Hadassah hospital in Jerusalem, said Mr Sharon had suffered "a significant stroke," adding that he was "under anaesthetic and receiving breathing assistance". A few minutes later, Dr Mor-Yosef said that initial tests showed Mr Sharon had suffered cerebral bleeding.
Mr Sharon was put in an ambulance at his ranch in the Negev desert after complaining he was feeling unwell. Dr Shmuel Shapira of Hadassah hospital said the stroke developed while Mr Sharon was being taken to the hospital in Jerusalem.
He said Mr Sharon had suffered "a massive stroke" and that he was taken to an operating room to drain the blood.
TV station Channel 2 reported that Mr Sharon was suffering from paralysis in his lower body.
On December 18, Mr Sharon was taken to hospital after suffering a mild stroke. Doctors said he would not suffer long-term effects from the stroke, but they discovered a birth defect in his heart that apparently contributed to the stroke.
The downturn in the prime minister's health comes as Mr Sharon prepares to run for re-election on March 28 at the head of the new centrist party, Kadima, after quitting the ruling Likud party in November.
The White House tonight offered their "thoughts and prayers" to Mr Sharon and his family. "Laura and I share the concerns of the Israeli people about prime minister Ariel Sharon's health, and we are praying for his recovery," the US president, George Bush, said in a statement.
Une nouvelle hémorragie cérébrale a conduit à une troisième opération d'Ariel Sharon. Après un examen au scanner vendredi matin, les médecins ont décelé une reprise de l'hémorragie nécessitant une nouvelle intervention. Ariel Sharon avait déjà subi deux interventions de ce type auparavant. 

Mor Yossef a dit que l'équipe médicale avait constaté une montée de la pression intracrânienne, des changements de pression sanguine et la présence d'une zone d'hémorragie. Les médias ont rapporté que l'opération avait duré trois heures.