Israeli Prime Minister Ariel Sharon suffered a 'massive' brain haemorrhage this evening.
'There is massive internal bleeding in the brain. He has been in the operation room for an hour,' Dr Shmuel Shapira told Israel's Channel Ten television.
Mr Sharon, who is 77, was admitted to hospital early this evening for a planned heart procedure after feeling unwell.
He had been due to go into hospital tomorrow morning in any case, after temporarily handing over authority to Finance Minister Ehud Olmert.
The planned procedure, a so-called cardiac catheterisation, followed a minor stroke last month.
Mr Sharon was at his Sycamore farm residence in southern Israel when he began to feel unwell, and was immediately transported to the Hadassah hospital in Jerusalem.
Israeli radio said he remained conscious.
