Israel's Maariv newspaper said early January that Washington was pushing a plan to restart peace talks that foresees reaching a final deal in two years and agreeing on permanent borders in nine months.
Under the plan, the Israelis and Palestinians will immediately start final status talks that were suspended during the Gaza war a year ago, Maariv reported, citing unnamed sources.
Mitchell last visited Lebanon in June vowing at the time that Washington would not sacrifice the tiny Mediterranean country as it seeks to reach comprehensive peace in the Middle East.
US envoys' visits are criticised by Lebanon's Shiite Hezbollah, which the United States lists as a terrorist organisation.
On Monday, Hezbollah MP Hassan Fadlallah slammed such visits to Beirut in a radio interview, saying they did "not serve the interests of Lebanon."
Mitchell's latest Mideast tour comes less than a week after US President Barack Obama's national security adviser James Jones held talks with Palestinian and Israeli leaders aimed at furthering US-led peace efforts.
Obama has been struggling to get the two sides back to the negotiating table since he assumed office nearly a year ago but has thus far failed to get Israel to completely halt settlements or secure Arab concessions to the Jewish state.
The Palestinians have said they will not resume talks -- suspended a year ago during Israel's war on Hamas in Gaza -- until Israel halts all settlement building in the occupied territories.
Israel has enacted a 10-month moratorium on new settlement projects but has excluded mostly Arab east Jerusalem, public buildings and projects already under way. The Palestinians have rejected the move as insufficient.
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