A top Yahoo official who has come under fire for the company’s role in the 2004 imprisonment of a dissident in China apologised on Thursday for failing to tell US lawmakers that Yahoo knew more about the case than he initially acknowledged in testimony last year.

Michael Callahan, Yahoo’s executive vice president and general counsel, said in a statement ahead of a congressional hearing next week that he “realised” that Yahoo had additional information about the nature of the probe into one of its users, Shi Tao, a journalist now serving a 10-year prison sentence in China, months after he testified that Yahoo had “no information” about the investigation.