The United States, Russia, the European Union and the United Nations on Tuesday attacked Israel's move to expand a West Bank settlement as a threat to peace efforts. The new public condemnation of Israel came amid intense efforts by Tony Blair, the diplomatic Quartet's special envoy, to get the Palestinians and Israelis back into direct talks, diplomats reported. "The Quartet is greatly concerned by Israel's recent announcements to advance planning for new housing units in Ariel and east Jerusalem," the four said in a statement. "This comes at a critical juncture with Quartet efforts ongoing to resume negotiations which are the only way to a just and durable solution to the conflict," added the statement. Israel on Monday approved the building of 277 new homes in Ariel, a Jewish settlement inside the occupied West Bank, taking the total to more than 2,700 new settler homes approved in the past two weeks. The planned expansion has brought a furious response from the Palestinian Authority, which has shunned direct talks since Israel ended a moratorium on settlement building in September last year. Israel has rejected the international criticism, insisting that the settlements are not an obstacle to direct talks. "The Palestinians have negotiated many times when settlements were in existence," said Israel's UN ambassador Ron Prosor. "Prime Minister Benjamin Netanyahu put in place a freeze on settlements, during which Palestinians waited nine months to come back to the table. Why? They have learned that it is better for them to sit back and do absolutely nothing." The two sides are building up to a new diplomatic confrontation as Palestinian president Mahmud Abbas prepares to seek full United Nations membership at the UN General Assembly in September. Israel says this is a threat to the peace process and the United States is expected to veto any application to the UN Security Council. "The Quartet reaffirms that unilateral action by either party cannot prejudge the outcome of negotiations and will not be recognized by the international community," said the statement. "Jerusalem in particular is one of the core issues that must be resolved through negotiations between the parties, which underscores the urgent need for the parties to resume serious and substantive talks," the international powers added. The Quartet has itself been divided in recent months over how to end the conflict that it has been trying for years to settle. UN chief Ban Ki-moon, EU foreign policy chief Catherine Ashton, US Secretary of State Hillary Clinton and Russian Foreign Minister Sergei Lavrov held a meeting in Washington last month and could not even agree a statement about the encounter. The European powers want the Quartet to take a stronger role in efforts to get the Palestinians and Israelis back to the negotiating table, even if this means setting out the parameters for talks. The United States has pushed back such a move, diplomats said. Former British prime minister Blair, who has been the Quartet's special envoy since 2007, is working on a Quartet communique which he hopes could end divisions between the international powers and help get talks started again before the UN assembly. "Those efforts are still going on. Tony Blair is in the center of efforts trying to find the relevant wording to move forward," said a senior diplomat at the United Nations. "Mr Blair is making progress. If you are talking about success -- not yet," the envoy told reporters, speaking on condition of anonymity.