Google has once again come under the cross-hairs of anti-trust investigators, this time in the USA.

Reuters report that a large number, reportedly 37, U.S. state attorneys general have filed an antitrust lawsuit in federal court against Alphabet Inc’s Google.

The charge related to the case, which has been filed in U.S. District Court for the Northern District of California, has not been specified, but it is expected to be around the android app store, according to Reuter’s “sources familiar with the matter.

Politico reports the case is about Google’s plan to force developers who use the Play Store to pay a 30 percent commission on sales of digital goods or services, similar to the way Apple does.

Google has been found guilty in the EU of abusing its position in the mobile market to limit competition from alternate mobile operating systems and the company was recently fined $267.48 million after admitting to favouring its own ad exchange over competitors.