The U.S. is intensifying the hunt for bribes paid overseas and is warning corporations to cooperate—or else.

Using funds from the billions of dollars seized from criminals, the government is committing more agents, attorneys and accountants to the mission. With 40 new lawyers and FBI agents dedicated to foreign-bribery probes, investigators have begun working out of specialized anti-bribery units across the country as they chase hard-to-get evidence about crooked deals in Asia, Africa and South America.

"We're trying to leverage" companies into reporting suspected bribes by their workers "because often only they have the ability to get that information," Assistant U.S. Attorney General Leslie Caldwell said in an interview. "We expect that with new agents and our prosecutors out there," companies "will think significantly about self-reporting."