Olmert is criticised for suggesting peace talks with the Palestinians.
Haniya said the conference “carries grave risks for the Palestinian cause and the entire region”, adding that Israel and the United States would use it “as an occasion to provide new and more concessions”.
Hamas, which seized control of Gaza in fighting with Abbas’s Fatah forces in June, has repeatedly called on Palestinians not to participate in the peace conference to be held near Washington.
Saeb Erekat, a senior Abbas aide, said in an Israeli television interview on Thursday that Abbas was determined to make the conference succeed and that he could resign if the talks failed. But he also said that success would end Hamas’s reign in Gaza.
“When I say that Abu Mazen [Abbas] is not glued to his chair, I really mean it. It’s not that he doesn’t want to serve his people, but failure to produce an agreement will change the dynamics of thinking and thought within the Palestinian society,” Erekat told Israel’s Channel 10.