Microsoft and Yahoo have officially joined opponents to Google's controversial deal with US publishers and authors to scan millions of books and make them available online.
US media reports said submissions from the two tech companies were among a flurry of final supporting and opposing arguments lodged with the US court to rule on the legality of the deal.
If approved, Google will pay $125m to book publishers and authors in return for the right to give US internet users partial access to out-of-print books still in copyright, unless rights holders opt out.
Money from selling full access will be split between Google and the rights holders.
Although the deal will only cover US copyright interests, it will involve books published elsewhere and has raised concerns in Europe that it will affect international copyright law and give a US company control over online access to European learning.
At least two European countries, France and Germany, lodged objections to the US deal as European stakeholders gathered in Brussels to discuss the deal and Europe's strategy for digitising the region's libraries.
The digital books dispute has also attracted the attention of the US government, with the House Judiciary Committee calling a hearing on the issue tomorrow, according to the Financial Times.
Microsoft and Yahoo joined others in opposing the deal on the grounds that it will create a monopoly that will drive up book prices and further boost the dominance of Google's search engine.
Digital book monopoly
In their submission to the US court, Microsoft's lawyers accused Google of seeking a monopoly on digital books.
"Monopolisation is the wrong means to carry out the worthy goal of digitising and increasing the accessibility of books," they wrote.
Yahoo's lawyers said the settlement was "not an appropriate legislative vehicle".
The deal "covers an unascertainable, and conflicted, group of plaintiffs" and "raises competition concerns", while also creating "barriers to entry for future competitors to Google in presenting books online", they said.
Google and the deal's supporters argue that it will benefit society by making millions more books available to anyone with web access.