Republican senators on Tuesday attacked the chief executives of Facebook and Twitter for what they called censorship of President Donald Trump and his allies during the US election while Democrats bemoaned the spread of misinformation on social media.

The CEOs, Jack Dorsey of Twitter and Mark Zuckerberg of Facebook, defended their content moderation practices at a congressional hearing scheduled after the platforms decided to block stories from the New York Post that made claims about the son of then-Democratic presidential candidate Joe Biden.

The move incited uproar among Republican lawmakers who have consistently accused the companies of anti-conservative bias...