JERUSALEM (Reuters) - Doctors plan to perform on Sunday a tracheostomy on Israeli Prime Minister Ariel Sharon, a surgical procedure that will help wean him off a respirator, a hospital statement said.

The tracheostomy, an incision in the windpipe that forms a temporary or permanent opening, will replace a tube now lodged in the throat of the 77-year-old leader, who suffered a massive stroke on Jan. 4.

A tracheostomy is routinely performed on many stroke victims to reduce the risk of infection posed by intubation.

"The prime minister's condition continues to remain critical but stable," said a statement issued by Jerusalem's Hadassah hospital, where doctors have been trying, so far unsuccessfully, to rouse Sharon from a medically induced coma.

"This evening the prime minister will undergo a CT test after which he will undergo a tracheostomy. The surgery is aimed at helping to wean him off a respirator machine. It will be conducted in the operating room under general anaesthesia."

Once the tracheostomy is performed, surgeons can connect oxygen and suction tubes to the hole in Sharon's windpipe.