US Special U.S. envoy George Mitchell has said that the Israeli Navy's raid on a flotilla must not undermine indirect negotiations he is mediating between Israel and the Palestinians. Speaking in the West Bank town of Bethlehem today, Mitchell said the incident – in which nine foreign activists were killed – showed the need for progress in the talks that got under way last month.According to Israeli media Haaretz, during the talks with Mitchell yesterday, the Palestinian president, Abbas demanded an end to the Israeli blockade of Gaza. He also called for an international investigation headed by the United Nations Security Council into the Israeli attack on the ships. Abbas is due to meet U.S. President Barack Obama in Washington on June 9.