Former Israeli prime minister Ariel Sharon’s health has deteriorated further, with his “vital organs” failing, says the hospital where he’s been housed in a comatose state for eight years.

“In the last few days, we have seen a gradual decline in the functioning of Ariel Sharon’s vital organs, which are essential for his survival,” Tel Hashomer hospital director Zeev Rotstein told public radio on Thursday.

“His state is classed as critical, meaning his life is in danger,” Rotstein said.

“The medical staff and Sharon’s family are expecting a turn for the worse,” he added.

The 85-year-old’s health worsened on Wednesday, as Sharon suffered from “serious kidney problems” after undergoing surgery, Israeli media reported.

News website Ynet quoted medical sources as saying Sharon was taken into intensive care a month ago. His health then stabilised but suffered a “significant deterioration” in the past few days.

The long-time leader of the right-wing nationalist camp in Israeli politics suffered a massive stroke on January 4, 2006, slipping into a coma from which he has never recovered.

Israeli and US specialists said a year ago that Sharon had showed “significant brain activity” in an MRI scan, responding to pictures of his family seven years after the stroke.

Concern over the state of Sharon’s health comes as US Secretary of State John Kerry arrived in Israel at the start of a four-day Middle East visit aimed at securing Israeli and Palestinian agreement on a framework for final status peace talks.

“Our thoughts, my thoughts, are with the Sharon family,” Kerry said ahead of a meeting with Prime Minister Benjamin Netanyahu.

“We remember his contributions, the sacrifices he made to ensure the survival and the wellbeing of Israel,” he said.

Sharon was first elected prime minister in February 2001, just months after walking through east Jerusalem’s flashpoint Al-Aqsa mosque compound, revered by Jews as the Temple Mount, in an action that sparked the second Palestinian uprising.

Nothing could redeem Sharon in the eyes of his Palestinian foes. Shortly after his massive stroke in 2006, Hamas said the Middle East would be better off without him.

Dubbed “the Bulldozer” both for his style and his physique, Sharon is also remembered by Arabs as the “Butcher of Beirut” for the massacres of Palestinian refugees at Sabra and Shatila by a Lebanese militia, while Israeli troops stood by.