Former Israeli PM Ariel Sharon's health is "deteriorating" with his "vital organs" failing, hospital officials have said.

The 85-year-old has been in a coma for almost eight years after suffering an incapacitating stroke from which he has never recovered.

Doctors at the Tel Hashomer hospital said his health has declined to a "critical" condition and his "life is in danger".

Zeev Rotstein, director at the facility, said: "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."

"His state is classed as critical, meaning his life is in danger.

"The medical staff and Sharon's family are expecting a turn for the worse."

Sharon's family were by his bedside, he added.

In an MRI scan in January last year, Sharon showed "significant brain activity" and was found to be responding to family photographs.

His condition reportedly started to worsen on Wednesday when he suffered serious kidney problems after an operation.

The long-time leader and architect of Israeli settlements in occupied Palestinian territory was first elected prime minister in February 2001.

In a surprise move, he left the right-wing Likud four years later to set up a new party, Kadima, frustrated by hardliners opposed to his withdrawal of troops and settlers from Gaza in 2005, and to any further concessions in the occupied West Bank.

The iconic and controversial figure suffered a massive stroke on January 4, 2006, slipping into a coma at the height of his political power.