Facebook Inc.'s Mark Zuckerberg was prepared to cite competition with China if asked whether the social media giant should be broken up, according to internal notes the chief executive officer took to a congressional hearing on Tuesday.

"Break Up FB? U.S. tech companies key asset for America; break up strengthens Chinese companies," read the document, which was photographed by the Associated Press.

Zuckerberg was speaking during the first of two days of testimony to Congress after a data leak sparked the worse crisis in the company's history. During a break, some journalists snapped pictures of his notes.