Odebrecht SA, the Brazilian construction giant, paid at least $32.5 million in bribes in Colombia—three times the amount it confessed to almost two years ago when it admitted to carrying out one of the largest graft schemes in corporate history, Colombia’s attorney general said.

In an interview in his Bogota office, Attorney General Nestor Humberto Martinez described a deeper and more pervasive scandal than the one Odebrecht admitted to in a 2016 plea agreement with Brazilian and U.S. authorities. That agreement listed $11.1 million in bribes paid to win two Colombian infrastructure projects as part of a plot that reached...