Palestinian Authority Chairman Mahmoud Abbas warned Wednesday that a US-sponsored international peace conference planned for November could fail if no plan for a solution to the Israeli-Palestinian conflict was devised ahead of the meeting. Following closed-door talks with Jordan's King Abdullah II in Amman, Abbas told state-run Jordan Television that the proposed conference "lacked clarity." He said he did not know an official date, other than mid-November, for the conference and was unsure who would attend. "The third issue is related to the content of the meeting," Abbas said. "If we go to a conference without clarity on a solution and without a declaration of principles within the framework of a work plan, I don't think that the conference will be beneficial." On Tuesday, Abbas and Prime Minister Ehud Olmert tackled the core issues that have tormented Mideast peacemakers for decades - Palestinian refugees, final borders and the fate of Jerusalem. It was the first time both leaders addressed such issues in depth and represented an important building block for the fall peace conference. In Amman on Wednesday, Abdullah discussed with Olmert in a telephone conversation the efforts to "push forward the peace process between Palestinians and Israelis," the official Petra news agency reported. It did not say if Abdullah's call to Olmert was after his meeting with Abbas. Abbas said he briefed Abdullah on his talks with Olmert and outlined the "daily hardships" facing the Palestinian people, including Israeli delays at checkpoints and prisoners held in Israeli jails. A royal palace statement said Abdullah backed Palestinian demands that Israel engages in discussions on the core issues in their conflict to "guarantee the success of the international peace conference." Abdullah said Palestinians should "unify" their ranks to achieve their goal for statehood - a reference to the conflict between Abbas's Fatah faction and the militant Hamas, which took over the Gaza Strip in a bloody coup in June. The king also repeated his call on the international community to provide urgently needed economic assistance to improve Palestinian living conditions, especially in the Hamas-ruled coastal strip.