Britain said on Wednesday it will abstain on a vote for upgraded Palestinian status at the United Nations unless the Palestinians commit to an immediate return to negotiations with Israel.
Foreign Secretary William Hague said Britain would only support Palestinian president Mahmoud Abbas in the vote on Thursday if he agreed to talks over a lasting two-state deal with Israel.
To secure Britain's vote, Hague said the Palestinians would also have to drop their pursuit of International Criminal Court (ICC) jurisdiction over the Occupied Territories and confirm that the UN resolution would not reply retrospectively.
"Up until the time of the vote itself, we will remain open to voting in favour of the resolution if we see public assurances by the Palestinians on these points," Hague told parliament.
"However, in the absence of these assurances the United Kingdom would abstain on the vote."
He added that the assurances could be made either in the text of the Palestinian resolution, or in accompanying statements.
Abbas is to submit a formal application to the UN General Assembly in New York on Thursday to obtain an upgraded role from an observer entity to that of a non-member observer state.
A growing number of European countries have pledged to vote in favour of the motion, among them France, Spain, Norway, Denmark and Switzerland, but the move is strongly opposed by the United States and Israel.
If the request is approved by the 193 member states of the General Assembly, it will give the Palestinians access to a range of UN agencies and also potentially to the ICC.