BENGHAZI - The UN envoy to Libya will discuss with rebel leaders on Monday informal plans for a negotiated end to the war as Western powers ramp up diplomatic and military pressure on Muammar Gaddafi to step down.Abdul Elah al-Khatib arrived in the eastern rebel stronghold of Benghazi on Monday, rebels said, as a diplomatic push to end the conflict gathers steam.In an apparent further sign of moves towards a political solution, a senior rebel leader was quoted as saying that Gaddafi and his family could remain in Libya provided they gave up power.A European diplomat said last week that Khatib would try to persuade warring parties in Libya to accept an informal plan that envisages a ceasefire followed by the creation of an interim power-sharing government, but with no role for Gaddafi.