Labour MP Sarah Champion highlighted figures suggesting 79 people have been killed on such roads.
Around 10 per cent of England’s motorway network is made up of smart motorways.
They involve various methods to manage the flow of traffic, such as converting the hard shoulder into a live running lane and variable speed limits.
But there have been long-standing safety fears following fatal incidents in which vehicles stopped in live lanes without a hard shoulder were hit from behind.
Ms Champion, whose Rotherham constituent Jason Mercer was killed on a smart motorway in South Yorkshire in 2019, told the House of Commons: ‘The Prime Minister said ”smart motorways are unpopular because they are unsafe. We need to listen to drivers and stop with the pursuit of policies that go against common-sense”.
‘Since then three new schemes have gone live with three more expected shortly.
‘Prime Minister, especially during a cost-of-living crisis, how do you justify pushing ahead with these death trap roads?’
Mr Sunak replied: ‘Safety on our roads is our absolute priority and we will do everything we can to make sure drivers do feel safe.
‘Last year, we in fact paused the rollout of smart motorways not already in construction while we consider the data and next steps.