Palestinian deputy Prime Minister Nabil Shaath said Sharon's illness deepened uncertainty about the peace process.
"On a purely humanitarian level we feel sorry for Mr. Sharon. Politically it will increase the uncertainty we are facing to get back to the peace process," he said. "It is highly unpredictable to tell what will happen."
But a radical Palestinian leader in Damascus, the Syrian capital, called Sharon's health crisis a gift from God.
"We say it frankly that God is great and is able to exact revenge on this butcher. ... We thank God for this gift he presented to us on this new year," Ahmed Jibril, leader of the Syrian-backed faction Popular Front for the Liberation of Palestine-General Command told the Associated Press.
He said Sharon's legacy would be one of huge damage inflicted on the Palestinian people.
A Palestinian commentator on the Saudi-owned Al-Arabiya network offered Sharon unexpected praise as "the first Israeli leader who stopped claiming Israel had a right to all of the Palestinian's land," a reference to Israel's recent withdrawal from the Gaza Strip.
"A live Sharon is better for the Palestinians now, despite all the crimes he has committed against us," said Ghazi al-Saadi.
The Qatar-based Al-Jazeera aired an extended interview with Sharon adviser Raanan Gissin, who explained the Israeli leader's condition and treatment.
Sharon's illness cast a huge shadow across the political life of the region, where the Palestinians were to vote in parliamentary elections January 25 and Israel slated a nationwide vote March 28.
'This is a big event'
In Lebanon, Osama Hamdan, a key figure in the militant Hamas group, told AP he saw no justification for postponing the Palestinian vote because of the political turmoil in Israel.
"On the contrary, it could be an opportunity for the Palestinians to take advantage of the jolt caused by Sharon's absence to conduct an election away from pressures. Sharon out of the picture is a way out for Palestinians to escape the pressures," he said.
After Sharon's first mild stroke on December 18, reaction in the Palestinian street was mixed, with some celebrating his illness and others wishing he would recover because they believe only he can strike a peace deal with the Palestinians.
In Beirut, a newspaper editor said he feared Sharon's absence from the scene could lead to more Israeli-Palestinian violence.
"This is a big event," said Sateh Noureddine, managing editor of Lebanon's As-Safir newspaper. If Sharon dies, it "could lead to the postponement of the Palestinian elections and the Israeli elections and possibly could lead to a security deterioration," he told AP.
He predicted, however, the repercussions would largely be limited to the Israeli-Palestinian conflict.
"It's a quake, whose aftershocks will be local – Israeli and Palestinian – because the (Mideast) conflict has become a Palestinian-Israeli one," Noureddine told AP.
Ali Badwan, a Palestinian living in Damascus, said Sharon was "the dinosaur of the Israeli political right and his legacy was the bloodiest of any Israeli against the Palestinian people. ... The Palestinian people would not mourn his passing from the political scene."
Palestinian refugee camps were quiet in Syria and Lebanon, with many residents engrossed in television coverage of Sharon's illness.
Reuters contributed to the report