Dozens of state attorney generals are set to launch separate antitrust investigations into Facebook and Google as early as next week, which will add to the scrutiny the tech giants are already facing from a federal probe.

The Google investigation is expected to be announced on Monday outside the U.S. Supreme Court and will be spearheaded by Republican Texas Attorney General Ken Paxton, sources told the Wall Street Journal.

Meanwhile, Democrat New York Attorney General Letitia James will be leading an overlapping group of attorneys general in a probe of Facebook.

'Even the largest social media platform in the world must follow the law and respect consumers,' James said.

Dozens of state attorneys general are set to launch separate antitrust investigations into Facebook and Google as early as next week. Pictured is Facebook's Mark Zuckerberg

The investigation into Facebook will be led by New York State Attorney General Letitia James (seen here at a news conference in New York City in June)

James announced the investigation on her Twitter feed on Friday

'I am proud to be leading a bipartisan coalition of attorneys general in investigating whether Facebook has stifled competition and put users at risk.

'We will use every investigative tool at our disposal to determine whether Facebook’s actions may have endangered consumer data, reduced the quality of consumers’ choices, or increased the price of advertising.'

Facebook says it plans to work constructively with state attorneys general who are launching the antitrust probe.

Facebook's Will Castleberry, a vice president of state and local policy, said in a statement Friday that the company welcomes a conversation with policymakers about the competitive environment in which it operates.

Castleberry says people have multiple choices for every one of the services Facebook provides.

He also says that if Facebook were to stop innovating, people could easily leave the platform.

The investigation into Facebook will be led by New York in cooperation with the attorneys general of Colorado, Florida, Iowa, Nebraska, North Carolina, Ohio, Tennessee, and the District of Columbia.

The attorneys general will reportedly be looking at the possible harm to consumers from Google's impact on digital advertising, as well as investigating concerns over Facebook's control of personal data.

Google has said that it was cooperating with the state officials but Facebook has not commented.

Sources say the probes by the attorneys general, which have been speculated for several weeks, could be expanded to include other tech giants.

The tech giants, among the richest and most powerful companies in the world, are facing increasing antitrust scrutiny from Congress, federal agencies and now the 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 anti-competitive practices. The investigation is believed to be aimed at Google, Amazon and Facebook, and potentially Apple.

Separately, the Federal Trade Commission, which also enforces antitrust law, is also probing Amazon and Facebook to determine if they abused their massive market power in retail and social media, respectively.

The state action coincides with a move by the Department of Justice, which announced its own antitrust review into big tech last month.

The Google investigation is expected to be announced on Monday outside the U.S. Supreme Court. Google has said that it was cooperating with the state officials. Google CEO Sundar Pichai is seen above in San Francisco in 2018

The investigation into Google will be led by Texas State Attorney General Ken Paxton (seen above during a news conference in Austin in 2015)

The big four - Google, Facebook, Apple and Amazon - have been accused of using their marketplace dominance to bulldoze opposition.

The Justice Department said last month it is reviewing 'whether and how market-leading online platforms have achieved market power and are engaging in practices that have reduced competition, stifled innovation, or otherwise harmed consumers.'

Social media companies have frequently been accused of a heavy-handed approach to conservative views and having employees with a liberal bias.

In July, around a dozen state attorneys, both Republican and Democrat, met with DOJ officials in Washington to discuss their concerns with the tech industry.

In addition to the state attorneys and the DOJ, the Federal Trade Commission, an independent government agency, is also looking into issues surrounding competitiveness in the industry.

U.S. regulators recently imposed a record $5 billion fine on Facebook for lapses in privacy and data protection, including the leaking of private data for political consultancy Cambridge Analytica.

Tech firms and their backers deny monopolistic conduct and argue the fast-evolving digital economy has robust competition and has led to lower prices and more choice for consumers