Turkey\'s prime minister has delivered a keynote speech at a regional meeting of the World Economic Forum, more than three years after he stormed off the stage in Davos, Switzerland, during a debate with the Israeli president. Recep Tayyip Erdogan opened the meeting in Istanbul on Tuesday with an address that highlighted Turkey\'s development in the past decade, but also touched on the Palestinian issue. Without mentioning Israel, he said Palestinians were kept in \"the largest open-air prison in the world.\" Palestinian President Mahmoud Abbas followed Erdogan at the podium, giving a speech that was sharply critical of Israel for the deadlocked peace process. The World Economic Forum holds its main, annual meeting in Davos. In the 2009 dispute, Erdogan said he would not return there. From The Daily Star