(Bloomberg) — U.S. Treasury Secretary Jacob J. Lew said the department is finishing work to limit the benefits companies gain from moving their addresses overseas even if his action won't be enough to stop the practice known as inversion.

Lew, speaking to reporters Sunday after a meeting of the Group of 20 finance ministers and central bankers in Cairns, Australia, reiterated that while the Obama administration wants to revamp the broader U.S. corporate tax code, "there is one loophole that should be shut down immediately — inversions."

"With the pace of these deals on the rise and no clear sign of when Congress will have legislation in place, Treasury is completing its work on administrative action to use our existing authority to limit the economic benefits of inversion," Lew said. "Administrative action cannot shut the door completely, and Congress will still need to act."