LONDON, Oct 29 (Reuters) - U.S. law firm Gardy & Notis, a shareholder rights advocate, said on Wednesday it was investigating AbbVie and its officers over statements made in connection with the drugmaker's failed move to buy Dublin-based Shire.

Gardy & Notis said it was asking investors to get in touch if they had lost money after buying Shire American Depository Receipts between June 20 and Oct. 14.

AbbVie Chief Executive Richard Gonzalez told investors in July that expected tax benefits were "not the primary rationale" for the combination but, in reality, the law firm said tax was a critical factor.

The U.S. firm ditched the planned $55 billion takeover after the U.S. government announced a change in treatment of so-called tax inversions, sending Shire shares into a tailspin.

(Reporting by Ben Hirschler; Editing by Greg Mahlich)