Avi Dichter said on Sunday it was fairly likely that violence would erupt again once Israel completed the construction of the separation wall.
Israel has built over half of the barrier.
Israeli officials said they expected the separation wall, which meanders into Palestinian territory in the West Bank, to be completed before the end of the year or, at the latest, during the first half of 2006.
Dichter suggested that with the absence of any significant political process towards a lasting resolution of the Israeli-Palestinian conflict, Palestinians would feel besieged.
He also suggested that the so-called stability of the present Palestinian Authority (PA) was not "all that assuring".
On Monday, Israeli and American media quoted Israeli Prime Minister Ariel Sharon as warning that the PA under Mahmud Abbas was "collapsing" and that Abbas seemed to be losing control.
PA officials have reacted strongly to Sharon's remarks, accusing him of only seeking to evade the "subject of settlements".
The separation barrier continues
to swallow up Palestinian homes
"Sharon is only trying to divert attention from the subject of Jewish settlement expansion in the West Bank," Zuhair al-Hamd Allah, head of the Israel department at the Palestinian Foreign Ministry, told Aljazeera.net.
Al-Hamd Allah said Sharon was not really sincere about implementing the road map peace plan or about "the success of the Abu Mazin (Abbas) government.
"Sharon is not really interested in protracted calm since this would remove the raison d'etre of the separation wall," al-Hamd Allah said.
However, the Palestinian official concurred with Dichter's assessment that violence could be inevitable "sooner rather than later", particularly if Israel continued to narrow Palestinian horizons and build Jewish colonies in the West Bank.
"If the road map is allowed to join the numerous other initiatives that evaporated because of Israeli intransigence, then the resumption of resistance will be a foregone conclusion," al-Hamd Allah said.
Palestinian leaders, including Abbas, have said they are willing to give the road map - backed by the quartet of the UN, US, EU and Russia - a chance.