A man holding a briefcase in a file photo. REUTERS/Toby Melville

NEW YORK (Reuters) - The U.S. Justice Department is increasing its prosecutions of alleged acts of foreign bribery by U.S. corporations, forcing them to take costly steps to defend against scrutiny, The Wall Street Journal reported on Monday.

At least 120 companies are under investigation, the paper cited Mark Mendelsohn, a deputy chief in the Justice Department division overseeing the prosecutions, as saying. That is up from 100 at the end of last year.

The effort began in the wake of a series of business scandals earlier this decade, including the collapse of Enron, that stirred up a corporate-reform movement, the paper said.

Today, companies across the United States are working to determine if they are at risk, the paper said In some instances, companies have called the Justice Department to come clean, in hopes of obtaining leniency, it added.