According to CBS News on Monday, 50 state Attorneys General, led by Texas, have launched an investigation into Google's "potential monopolistic behaviour".
"This is a company that dominates all aspects of advertising on the internet, as they dominate the buyer, seller and auction side," Texas Attorney General Ken Paxton was quoted as saying.
"If advertising costs are higher, advertisers pay more, and ultimately that's passed on to consumers," he added.
The European Union's anti-trust regulators in March fined Google 1.49 billion euros ($1.7 billion) for abusing its dominance in the online search market by blocking rivals.
Google has abused its market dominance by imposing a number of restrictive clauses in contracts with third-party websites which prevented Google's rivals from placing their search adverts on these websites, the European Commission (EC) said in a statement.
The Commission said the fine which is equivalent to 1.29 per cent of Google's turnover in 2018 takes account of the duration and gravity of the infringement.
The US Department of Justice in June said it was preparing to open a case against Google for potential anti-trust violations, thus, putting scrutiny on the tech giant amid a growing chorus of criticism about the power of Big Tech.
This comes at a time when there's a debate whether large technology companies should be broken up.
A separate group of US states announced an investigation into Facebook's dominance last week.
The Department of Justice, the Federal Trade Commission (FTC) and Congress are also conducting probes of both Facebook and Google.
In 2013, Google said it would change some practices after it agreed to a settlement with the US Federal Trade Commission. The FTC had been concerned that some of Google's business practices could stifle competition.
In 2010, the company received an anti-trust complaint from the European Commission regarding ranking of shopping search results and ads, which resulted in Google being fined $2.7 billion in 2017.
( With inputs from IANS )