The CEOs of Alphabet, Facebook and Twitter failed to dodge another appearance before the US Congress, with a Senate committee voting to compel them to answer questions about free speech and alleged political bias on their platforms.

Senators are keen to hear from Sundar Pichai, Mark Zuckerberg and Jack Dorsey before a Presidential election in November as part of a broader debate on overturning a law commonly known as Section 230, which protects social media companies from liability over content posted by users.

The executives declined to appear voluntarily.

Senator John Wicker, chair of the committee which voted to order them to attend a hearing, explained there are concerns Section 230 allows social media to stifle political debate and “determine what millions of Americans read, view and hear everyday”.

He said a congressional hearing would “increase transparency and accountability among big tech companies” and press the executives to reaveal how much influence their businesses hold over free speech “during a critical time in our democratic process”.

A date for the hearing has yet to be set.

Political posturing dominated a hearing the tech CEOs voluntarily attended in July which was meant to be focused on digital competition.