The U.S. Senate Judiciary Committee authorized subpoenas to Facebook and Twitter chief executives Mark Zuckerberg and Jack Dorsey to hear their side about accusations of anti-conservative bias, ramping up the pressure by the GOP on the social media giants' content rules before the U.S. Presidential elections.

Both Twitter and Facebook have long denied being biased when they arbitrate third-party content on their platform and have long held their neutrality. For instance, on Facebook, some of the site's heavy-trafficked content originate from conservative opinions.

The subpoena mandates Dorsey and Zuckerberg to testify about alleged "suppression and/or censorship" of the New York Post stories and "other content moderation policies, practices, or actions that may intervene with or influence elections for federal office," Nathan Ingraham, Engadget deputy managing editor, reported.

The two social media companies did not allow the New York Post story to be shared on its platform, which delved on U.S. presidential candidate Joe Biden's son Hunter and alleged emails that were taken from his laptop. The supposed "censorship" did not sit well with the Republicans, thus their cry for suppression.

Facebook and Twitter have been subjected to increasing censure from U.S. President Donald Trump and his GOP allies for restricting access to the NYP story on Biden and his son. The Judiciary body voted 12-0 to approve the subpoenas, with all Judiciary Republicans voting in favor.

The platforms, under mounting pressure to contain the spread of misinformation in the run-up to the election, had cautioned that the allegations made in the NYP story were baseless.

The ongoing issue is the latest in a litany of Republican legislators accusing Facebook, Twitter, and other internet groups of taking sides and shunning conservative voice, a perspective that experts say lacks convincing proof to merit credibility.

A Judiciary spokesperson had said that the panel is still discussing with the social media companies for their top bosses to possibly appear in a voluntary manner, instead of through subpoena.