New York's top attorney on Tuesday said its investigation into whether Facebook violated anti-trust laws has expanded to include most of the country.

The New York-led probe now includes 45 states along with the capital District of Columbia and the US territory Guam, according to New York attorney general Letitia James.

"Our investigation now has the support of 47 attorneys general from around the nation, who are all concerned that Facebook may have put consumer data at risk, reduced the quality of consumers' choices, and increased the price of advertising," James said in a release.

"We will use every investigative tool at our disposal to determine whether Facebook's actions stifled competition and put users at risk."

The leading online social network has become a popular target for elected officials and those seeking election, with topics of expressed concern ranging from privacy and advertising to Facebook backing a plan to launch Libra cryptocurrency.

"Even the biggest of the big tech companies should be held accountable, and that's what we're seeking to do with this investigation," Missouri Attorney General Eric Schmidt said of the New York-led probe.

Facebook chief Mark Zuckerberg has pledged to "go to the mat" to fight government attempts to break up the social media giant.

Zuckerberg has consistently argued that splitting the company would not address issues raised by critics.

Zuckerberg is scheduled to testify Wednesday on Libra before the House of Representatives.

The House Financial Services Committee said in a statement that Zuckerberg would be the sole witness at the October 23 hearing on "An Examination of Facebook and Its Impact on the Financial Services and Housing Sectors."

The hearing comes as Facebook's planned digital coin Libra faces heavy criticism from regulators and lawmakers in the United States and Europe.

Copyright Agence France-Presse, 2019