PALO ALTO, California — Secretary of State Condoleezza Rice yesterday blamed the apparent collapse of a truce in Lebanon on extremists trying to "sow discord" as she renewed the Bush administration's strong support of the Beirut government."I certainly hope that the Lebanese government will be able to deal with these extremists," Rice said. "It's just another example of extremists in the Middle East who are trying to destabilize democratic governments."

Rice made her comments in a joint appearance here with Australia's Foreign Minister, Alexander Downer. In Lebanon, heavy exchanges of gunfire erupted last night between Lebanese troops besieging a Palestinian refugee camp and Islamic militants holed up inside, breaking the two-day-old truce.

"The Lebanese government is, I think, very much trying to do the right thing here, to protect its population against the extremists who would sow discord and instability there," Rice said. "And I think the world is speaking out in favour of the Lebanese government."

Rice and Downer spoke privately about the Middle East and a range of other issues, aides said. But their public appearances together in the Silicon Valley emphasised their mutual admiration for innovation in this cradle of technology.

Rice's visit here was the second homecoming tour on which she has led a foreign minister. In October 2005, she lead British Foreign Secretary Jack Straw on a trip through her native Birmingham, Alabama.

The two began their day here at Stanford University, where Rice was provost before joining the administration. Rice made it plain at a visit to neighbouring Hewlett-Packard Co. that she intends to return to academia, calling herself a "soon-to-be-future professor again."