"I know I speak for all the board when I wish Ralph well, and all the very best for whatever he chooses to do next. Ralph's resignation is a great loss for ACC.''
The political backlash over the under-siege corporation intensified yesterday, with Mr Stewart's resignation triggering an urgent parliamentary debate over the changes needed at the state-owned accident insurer.
Mr Stewart, the former head of investment company AXA NZ, became chief executive of ACC in September last year but left yesterday morning after clocking up only nine months in the role.
Directors Rob Campbell and John McCliskie were also told they would not be reappointed to the board of ACC.
Mr Stewart said yesterday that he was "deeply frustrated that the benefits of the scheme and the great work we do has been overshadowed by recent events''.
Those events include a police decision last week not to lay charges against Ms Pullar, and TV3`s 60 Minutes programme on Sunday which implied it was ACC managers who first suggested a deal with her for the return of leaked data about thousands of clients.
ACC Minister Judith Collins said Mr Stewart told her on Tuesday "he felt it was time for him to move on''.