The Palestinians' current status is "permanent observer."
Britain will only support an upgrade if the Palestinians commit to return immediately to the negotiating table with Israel, The Daily Telegraph reported Wednesday.
"Up until the time of the vote itself, we will remain open to voting in favor of the resolution if we see public assurances by the Palestinians on these points. However, in the absence of these assurances, the United Kingdom would abstain on the vote," Hague said.
Germany also said it would oppose the move.
"Our goal in all this is to prevent further negative efforts on the already difficult Middle East peace process," German Foreign Ministry spokesman Andreas Peschke said.
France Tuesday said it will support the Palestinian bid to become a non-member U.N. "observer state," the foreign minister said, and Spain will do the same, El Pais reported.
"Thursday or Friday, when the question is asked, France will reply, 'Yes,'" Laurent Fabius told the French National Assembly Tuesday.
The U.N. General Assembly in New York is to debate the issue Thursday, the 65th anniversary of the U.N. decision to partition the territory of Palestine into Jewish and Arab states. The plan envisioned the creation of independent Arab and Jewish states and a special international regime for Jerusalem. The General Assembly adopted a resolution Nov. 29, 1947, recommending the adoption and implementation of the plan.
Israel accepted the proposal while the Palestinians and their Arab supporters rejected it, choosing war instead.
The Palestinian U.N. upgrade would imply recognition of Palestinian statehood, Fabius told lawmakers. But the "concrete expression of a Palestinian state" would come only through negotiations "without conditions" between Palestinians and Israel, he said.
Spain is also expected to vote in favor of the upgrade, despite a warning from Israel that such a move could limit Spain's influence in any future peace talks, Spanish newspaper El Pais reported.
The Netherlands and Italy, which were earlier expected to vote against the measure, will now probably abstain, the Israeli Foreign Ministry was quoted by Haaretz as saying.
The ministry now expects at least 15 of the 27 EU countries to vote in favor of the Palestinian resolution, with only Germany and the Czech Republic expected to vote against it, Haaretz said.
All told, at least 150 of 193 U.N. members are likely to support the move, the ministry said.
Israel will continue to honor the 1993 Oslo Accords, Haaretz said, ending the threat of punishment following the vote.
Sources close to Prime Minister Binyamin Netanyahu and Foreign Affairs Minister Avigdor Lieberman told the newspaper the government -- realizing General Assembly approval is inevitable -- is seeking to describe the vote as merely technical and procedural or as a symbolic Palestinian victory devoid of diplomatic significance.
But Israel does plan to put pressure on the Palestinian Authority, which governs parts of the West Bank and Gaza Strip under the Oslo Accords, the newspaper said.
For instance, Israel will stop ignoring the Palestinians' infringement of agreements between the sides, the newspaper said. In the coming months it will also deduct Palestinian debts, including more than $181 million in debt to Israel Electric Corp., from tax revenues Israel collects for the Palestinians, Haaretz said.
The move, allowed under the Oslo Accords, would stop two or three payments of Israel's monthly tax-money transfer to the PA, the newspaper said.