Israeli doctors say Prime Minister Ariel Sharon, who remains in a coma since suffering a stroke two weeks ago, underwent a surgical procedure overnight to replace his breathing tube.

The Hadassah hospital in Jerusalem issued a statement Wednesday morning, saying the procedure was necessary because the respiratory pipe developed a technical problem.

The statement said Mr. Sharon's condition continues to be critical but stable.

The 77-year-old prime minister has been on respirator since he was incapacitated by a brain hemorrhage on January 4.