The Recording Industry Association of America said Google's policy to demote pirate websites in search rankings was not working.
Google said in August last year that it was adding the number of valid copyright removal notices received for a website as one of more than 200 signals the company uses in its rankings.
"Sites with high numbers of removal notices may appear lower in our results," Google said in the blog post. The ranking change would help users find legitimate, quality sources of content more easily, it added.
Six months later, the RIAA has found no evidence that Google's policy had a "demonstrable impact on demoting sites with large amounts of piracy," it said in a statement on Thursday, while releasing a "report card" on Google's demotion policy.
"The sites we analyzed, all of which were serial infringers per Google's Copyright Transparency Report, were not demoted in any significant way in the search results and still managed to appear on page 1 of the search results over 98% of the time in the searches conducted," RIAA said in the report.
The websites also figured consistently in three to five of the top 10 search results, which is of concern as studies have shown that about 94 percent of users do not go beyond the first page of results, RIAA said.
Reputed and authorized download sites, such as iTunes, Amazon.com and eMusic, only appeared in the top 10 results for a little more than half of the searches, according to the study. For 88% of searches for MP3 files and downloads of popular tracks, Google's auto-complete feature suggested appending to the searches certain terms which are associated with sites for which it has received multiple notices of infringement, thus leading to illegal content, according to the study.
Google did not immediately comment. The company has been often criticized by the recording industry and music artists for facilitating piracy through its search engine and YouTube.
"I've found the same scenario with searches I've done," wrote Ellen Seidler, editor of Vox Indie blog. Piracy results remain top dog on Google search, she wrote in her blog post.
Google said in a blog post last year that between December 2011 and November 2012, it removed 97.5% of all URLs (uniform resource locators) specified in copyright removal requests. The number of copyright takedown requests increased tenfold in just six months to more than 2.5 million requests per week, it said in December.