Ariel Sharon (file photo)

Israeli Prime Minister Ariel Sharon underwent a tracheotomy Sunday, 11 days after his massive stroke. Doctors are worried.

Jerusalem's Hadassah Hospital says the tracheotomy took less than an hour and was successful. Doctors cut a small hole in Mr. Sharon's neck and inserted a tube into his windpipe. The aim is to wean him from a respirator which has helped him breathe since a massive stroke and cerebral hemorrhage early this month. Medical experts say the tracheotomy is another bad sign for the 77-year-old prime minister.

"The chances are very poor for recovery," said Israeli neurosurgeon Harry Rappaport. "We have to take into account the massiveness of the hemorrhage and his age and usually in such circumstances the prognosis is very bad."

Journalists and patients gather outside the Hadassah hospital in Jerusalem where Israeli Prime Minister Ariel Sharon remains in critical condition

Doctors are especially concerned that Mr. Sharon has not emerged from a coma, even though he has been taken off anesthetics. The Prime Minister's condition remains critical, but stable.