A view of Google's Beijing offices. File photo: VCG

More than 30 US state attorneys general are readying an investigation into Alphabet Inc's Google for potential antitrust violations, a source knowledgeable about the probe said on Tuesday.

Texas leads the group of 30-plus attorneys general, which plans to announce the probe on Monday, the source said.

Google said that it was cooperating with the state officials.

"We continue to work constructively with regulators, including attorneys general, in answering questions about our business and the dynamic technology sector," Google representative Jose Castaneda said.

The probe is focused on the intersection of privacy and antitrust, according to the source, who did not elaborate.

Ken Paxton, the Texas attorney general, filed comments along with 42 other state officials in June that urged the Federal Trade Commission to focus on privacy and data collection in investigating potential violations of antitrust law.

In the comment, the state officials argued that the big tech firms have such vast amounts of user data that it is hard for newcomers to compete.

Another Texas official, Assistant Attorney General Jeff Mateer, alleged in an FTC hearing in June that Google and other big tech companies were misleading in representing themselves as neutral, citing Google's balking at carrying an ad about what it means to be an American, the Texas attorney general's office said in a statement in June. 

Google eventually relented on the ad, the statement said.

The tech giants, among the richest and most powerful companies in the world, are facing increasing antitrust scrutiny from US Congress, federal agencies and now state attorneys general.

The Justice Department said in July that it was opening a broad investigation of major digital technology firms, focusing on whether they engage in anticompetitive practices. The investigation is believed to be aimed at big names like Google, Amazon.com Inc and Facebook Inc, and potentially Apple Inc.