Facebook Inc Chief Executive Mark Zuckerberg will strike a conciliatory tone Tuesday in testimony before Congress as he looks to fend off the possibility of new regulations as a result of the privacy scandal engulfing his social network.

The 33-year-old internet mogul is set to appear in Washington before a joint hearing of the U.S. Senate's Commerce and Judiciary committees some 15 or 20 minutes after the originally scheduled time of 2:15 p.m. (1815 GMT) because of a Senate vote.

Zuckerberg, who has never testified in a congressional hearing, said in written testimony Monday that he had made mistakes and had held too narrow a view of the social network's role in society.

Some 40 senators out of the 100-member Senate sit on the two committees holding Tuesday's hearing, setting up a possibly marathon hearing.

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