Updated

Treasury Secretary Jack Lew told members of Congress Wednesday that he will announce a new administrative effort this week to stop corporate inversions, as attempts at legislation to stop companies from moving their headquarters out of the U.S. have failed.

Lew said in a letter to lawmakers that he would issue "additional targeted guidance to deter and reduce further the economic benefits of corporate inversions."

Lew first took action to undercut the tax benefits of inversions in September 2014, announcing several specific rules meant to prevent companies from moving their headquarters abroad for tax purposes and limiting the tax breaks they could reap if they were successful in moving out of the country.

Wednesday's letter did not indicate what further efforts the Treasury could take.

Lew cautioned that only legislation could fully stop inversions, which are tax maneuvers in which U.S. companies merge with businesses in low-tax countries and then place the new headquarters of the combined company in the low-tax jurisdiction.

Read more on WashingtonExaminer.com