Tech giants YouTube and Google could be hauled before MPs after failing to honour commitments to take down extremist videos.
The companies pledged to take down content from illegal far-right terrorist group National Action at the Home Affairs Select Committee in December
Committee chairwoman Yvette Cooper, raising a point of order in the Commons, told MPs the videos were still widely available this week and accused YouTube of "failing to meet its basic responsibilities to tackle extremism".
She added: "There is widely available on YouTube this week the banned illegal propaganda videos from the extremist proscribed organisation National Action.
"Despite the fact that this video has been raised with YouTube and Google seven times by the select committee over the last 12 months, despite the fact that they have promised us that video is illegal and will be taken down and they would have the technology to prevent it being put back up."
The former minister said: "This is one of the richest companies in the world and is failing to meet its basic responsibilities to tackle extremists and protect public safety in this country."
Speaker John Bercow, responding to the point of order, told MPs the commitments "must be honoured" and informed Ms Cooper that she could write to him to allege "a contempt of the House" if action was not taken.
He said: "I share her intense concern on the matter. National action is, as I'm sure everybody in the House will agree, a despicable fascist neo-nazi organisation and my understanding is that it has been proscribed.
"If those commitments have been made, they must be honoured."
Home Secretary Amber Rudd said: "National Action is a proscribed group, I proscribed it myself.
"It is a terrorist organisation.
"The fact is that internet companies have made good progress in taking down Daesh-focused material.
"We have demonstrated that they can down with our own system, we showed them 94% of material that goes up from Daesh-type terrorist organisations but we need to see much more effort put into the particular area of the extreme right-wing groups."