The US Department of Justice has requested additional information from Microsoft and Yahoo, regarding their proposed partnership.

Both Microsoft and Yahoo confirmed Reuters that the Justice Department’s antitrust division had made a second request for documents, and that they would cooperate fully with the requests. Reportedly, the DoJs request for additional information means that the regulators would do a deeper examination into the deal.

In July, the two companies have announced a 10-year internet search partnership that will see Yahoo power its sites with the new Microsoft Bing search-engine technology, and Microsoft integrate aspects of Yahoo’s search software into its own web search platforms.

Under the deal, Yahoo will sell ads on both sites and will receive 88% of the revenue from all search ad sales on its sites for the first five years, which the company said would help boost its annual operating income by $500m.

Microsoft has agreed to pay $50m annually to Yahoo during the first three years of the 10-year internet search partnership. The companies have also agreed on a transition and implementation plan and a schedule for implementing Microsoft’s algorithmic search services and paid search services on all Yahoo Properties and Syndication Properties.

As part of the present review by the US DoJ, the two companies expect to be asked about their search-engine investments, ad pricing, and product plans, reported Bloomberg, citing a person familiar with the matter.