A former agent of a U.S. unit of Keppel Offshore & Marine Ltd., the world’s biggest builder of oil rigs, pleaded guilty in a scheme to pay bribes to Brazilian officials tied to the Petrobras scandal.

Zwi Skornicki, 69, admitted on June 25 that between 2001 and 2014 he participated in a plot to bribe Brazilian authorities and officials with Petroleo Brasileiro SA, Brazil’s state-owned oil company, to win business for Keppel.

“I agreed to pay bribes to Petrobras,” Skornicki told U.S. District Judge Kiyo Matsumoto in Brooklyn, New York. “In exchange for those bribes, we expected contracts would be...