§ 342-b. Recovery of damages by attorney general. In addition to existing statutory authority to bring such actions on behalf of the state and public authorities, the attorney general may also bring action on behalf of any political subdivision or public authority of the state upon the request of such political subdivision or public authority to recover damages for violations of section three hundred forty of this article, or to recover damages provided for by federal law for violations of the federal antitrust laws. In any class action the attorney general may bring on behalf of these or other subordinate governmental entities, any governmental entity that does not affirmatively exclude itself from the action, upon due notice thereof, shall be deemed to have requested to be treated as a member of the class represented in that action. The attorney general, on behalf of the state of New York, shall be entitled to retain from any moneys recovered in such actions the costs and expenses of such services.