Israel has been accused of wanting to "slowly liquidate" the jailed Palestinian leader, Marwan Barghuti.
A statement issued by Palestinian leader Yasser Arafat's Fatah movement said "Israel could not directly assassinate him and is now trying to slowly liquidate him," and warned Israel that "its crimes" would not go unpunished.
Barghuti, 44, narrowly escaped death in August 2001 when two Israeli missiles were fired at a convoy of cars he was travelling in, although Israel said it was trying to kill one of his entourage and not the Fatah chief himself.
The Fatah statement said Barghuti's detention in solitary confinement was "threatening his life", stressing his health "is deteriorating".
His wife Fadwa told journalists her husband's "lawyer visited him two days ago and informed me that he is suffering from chest pains and has difficulties breathing, and that the prison authorities had notsent for a doctor."
"He's in an underground room no larger than three square metres and only two metres (6.6 feet) high, without any air or light," she said.
Barghuti, seen by many as the inspiration behind the Palestinian uprising and as a possible successor to Arafat, was arrested by the Israeli army in April 2002 and brought before an Israeli court in September.
He faces various counts of murder and heading a terroristorganisation, and was moved to a prison in southern Israel andplaced in solitary confinement in early January.
One of his lawyers charged that Barghuti's life wasthreatened in the Ramla prison which he said is known for its harshdetention conditions.
PA