Google and Motorola must hand over key details of the Android operating system to Apple, a judge in a US patent case has ruled.

According to Bloomberg US Circuit Judge Richard A Posner also told Google and Motorola that details of the forthcoming acquisition of the latter by the former must also be provided to Apple in a court in Chicago yesterday.

Apple's attourneys had argued that "the Android-Motorola acquisition discovery is highly relevant to Apple’s claims and defences," in a filing last week, in the case that dates back to 2010.

Motorola, however, is adamant that despite its forthcoming takeover by Google, Google is not party to the lawsuit.

"Google’s employees and documents are not within the ‘possession, custody, or control’ of Motorola, and Motorola cannot force Google to produce documents or witnesses over Google’s objections," lawyers Motorola said in a court filing.

Apple filed a lawsuit against Motorola alleging six patent violations, with Motorola subsequently counter-suing Apple alleging three violations. The cases will be heard back-to-back in June, according to the report.