RAMALLAH, West Bank (AFP) - Palestinian President Mahmud Abbas said on Friday his Hamas rivals will "never" be able to take over the West Bank as they did the Gaza Strip, where they ousted his forces in 2007. "Hamas succeeded in its putsch in Gaza because we wanted to avert military confrontation, but what happened there would not be repeated in the West Bank. Never," Abbas told journalists. Hamas seized power in Gaza in June 2007, ousting forces loyal to the moderate Palestinian president after a week of deadly street battles. Abbas also said exiled Hamas supremo Khaled Meshaal would fail to set up an organisation to rival the Palestine Liberation Organisation, which the international community recognises as the legitimate representative of the Palestinian people. "He won't be able to destroy this edifice," he said in reference to the PLO. Meanwhile, US envoy George Mitchell said on Friday the United States is committed to "actively and aggressively" seeking lasting peace in the Middle East but warned there would be further setbacks. Speaking after touring a UN warehouse in Jerusalem packed with aid destined for the Gaza Strip, US President Barack Obama's Middle East envoy also called for a durable ceasefire in the ravaged Palestinian enclave. "The United States remains committed to actively and aggressively seeking a lasting peace between Israel and the Palestinians as well as between Israel and its Arab neighbours," he said at the UN Relief and Works Agency warehouse. "The tragic violence in Gaza and in south Israel offers a sobering reminder of the very serious and difficult challenges and, unfortunately, the setbacks that will come. "It is important to consolidate a sustainable and durable ceasefire while addressing immediately humanitarian needs," he said. Mitchell, who delivered his statement in front of pallets of flour and cooking oil bound for the impoverished coastal strip, announced that Obama "directed the use of another 20.3 million dollars to provide emergency food and medical assistance to the wounded and displaced in Gaza." He said the funds were in addition to about 40 million dollars that the United States has provided to humanitarian programmes in Gaza since hostilities broke out in December.