Google has been asked by Microsoft to remove more than 500,000 links from its index in the last month, figures show.
The vast majority of the links in question were ones which took people to sites connecting to pirated Microsoft software.
Google shared the statistics as part of its efforts to be more transparent about what influences search results.
Microsoft’s requests dwarf those of the British Phonographic Institute, which represents record labels.
It asked for 160,000 links to be removed, again because they gave people access to pirated content.
In a blog post explaining its decision to share the figures, Google said it had done so because it believed there should be transparency when “something gets in the way of the free flow of information.”
In the past it had shared information about official requests from government to get results removed from its search results and revealed when traffic to its services had been disrupted.
Now it has decided to broaden the range of information it shares to include requests from copyright owners.
“We remove more search results for copyright reasons than for any other reason,” a Google spokesman told the AFP agency.
The statistics shared on the copyright section of the Google Transparency Report show the number of requests to remove links has grown sharply.
In July 2011, the point at which its statistics start, Google was getting requests to remove 129,063 links per week. In May 2012 this figure had risen to 284,850. In the past month, more than 1.2 million links on 24,000 separate sites were removed. Requests to de-list links came from 1,296 separate copyright holders.
Google said it granted about 97% of requests to remove links and it usually took about 11 hours for any request to have an effect on search results.
Just under half of the requests for removals, which would mean that anyone searching for a particular term would not see blue links to those pages, came from Microsoft.
The BPI and media firm NBC Universal made the second and third largest number of requests in the last month.
“This data shows that placing all of the burden on copyright owners to deal with infringement is unworkable,” said BPI boss Geoff Taylor.
“It’s wrong for Google to be willfully blind to the clear data it has that particular sites are massive copyright infringers.”
“When Google has been told 100,000 times that sites like The Pirate Bay and beemp3 distribute music illegally, why do they come top – above Amazon and iTunes – when I search for ‘download music’?” he asked.
“It’s irresponsible, it misleads consumers and if Google won’t sort it out voluntarily, Government should get on with doing something about it.”