Hollywood's film academy said on Friday it was reviewing this year's campaigns for Oscar nominations, a day after a media report raised questions about the surprise nod for British actress Andrea Riseborough. On Tuesday, Riseborough was nominated for best actress for playing an alcoholic single mother in little-seen film "To Leslie," a shock to awards pundits who had not expected her to be in the mix. Media newsletter Puck reported on Thursday that the unexpected nomination had sparked questions about whether an aggressive campaign for Riseborough had violated lobbying rules set by the Academy of Motion Picture Arts and Sciences. The academy issued a statement on Friday that said the organization was "conducting a review of the campaign procedures around this year's nominees, to ensure that no guidelines were violated." The statement did not name Riseborough. The review also aims "to inform us whether changes to the guidelines may be needed in a new era of social media and digital communication," the statement said. The academy limits how studios can reach out to voters, how often and what they can say in any communications as part of their Oscars campaigns. Puck reported that the wife of the film director, actress Mary McCormack, and friends had "emailed and called tons of members of the Academy's actors branch, begging them to see the little-watched alcoholic drama and post online about Riseborough's searing performance." Dozens of A-list stars then "sang her praises and helped win her the coveted nomination," Puck said. Representatives for McCormack and Riseborough did not immediately respond to requests for comment. "To Leslie" has collected $27,000 at movie box offices since its release in October, according to Box Office Mojo. "We have confidence in the integrity of our nomination and voting procedures, and support genuine grassroots campaigns for outstanding performances," the academy statement said. Winners of the Academy Awards will be announced on March 12.