The MP who chairs Parliament’s influential education committee says the government has “yet to prove the case” for new grammar schools following an inquiry into ministers’ plans to expand selection in England.

Neil Carmichael says the government must demonstrate how opening new grammar schools will aid social mobility and improve education outcomes for all children after his committee warned the policy “would have effects throughout the education system”.

Ministers want to lift the ban on new grammar schools and are offering existing selective schools a share of a £50 million annual funding pot for expansion.

The focus on opening new grammar schools is, in my view, an unnecessary distraction

However, MPs on the education committee remain unconvinced by the government’s proposals following an inquiry which took evidence from the schools minister Nick Gibb and a host of academics.

“The government has yet to prove the case for opening a new wave of grammar schools,” Carmichael said.

“The prime minister rightly talks of making Britain a great meritocracy. If the government wants to push ahead with new grammar schools it must demonstrate how this aids social mobility and improves educational outcomes for all, most especially those from disadvantaged backgrounds.”

According to the committee, the policy aims set out by the government in its schools that work for everyone consultation “differ significantly from the characteristics of grammar schools of the past and present”, especially when it comes to closing the attainment gap.

MPs also want the government to demonstrate how the creation of new grammar schools will help close the gap in all schools, not just for individual pupils, and have called for a “thorough assessment” of the impact greater selection could have on all schools.

Caution should also be used “when making comparisons between high- and mixed-ability pupils at selective and non-selective schools”.

“It is important that, where comparisons are made, wider socio-economic issues are taken into account,” the report says.

Meanwhile, selection tests “should not be the only basis on which admissions to grammar schools are based”. The committee claims ministers have yet to demonstrate “how an admissions system could be designed in a manner which would be immune to gaming, or being reduced to the ability to pay”.

Carmichael, a noted grammar school sceptic, called the policy “an unnecessary distraction from the need to ensure all our young people are equipped with the skills to compete in the modern workplace”.

“A broadly skilled workforce is crucial to the future success of the UK economy,” he said. “If the government is committed to increased specialisation in our education system then they should spell out how this meets the aims of the industrial strategy and the goal of an economy that works for all.”