Ministers have been accused of trying to act tough over proposed education reforms that would emphasise excluding unruly children from schools and using “reasonable force” against them.

The plans are outlined in leaked documents seen by the Guardian that also set out government plans to announce within days billions of pounds in new funding and a further wave of free schools.

“We know the role that school exclusions have played in the rise of knife crime, but once again the Tories are trying to sound tough whilst failing to look at the evidence,” said the Liberal Democrat education spokeswoman, Layla Moran.

“The Conservative government would rather kick kids out of school and advocate the use of the ambiguously termed ‘reasonable force’ as discipline, which will cause parents, children and teachers additional stress, rather than actually putting the time and investment in to ensure all children receive a good education and have a positive experience within our schools.”

Richard Crellin, the policy manager at the Children’s Society, said the charity was deeply concerned at any policy that made exclusions easier. “We know that excluded pupils can be targeted by criminal gangs and exclusion is often linked to unmet mental health needs.”

The documents also include plans for a £3.5bn funding announcement and proposals to increase teachers’ basic pay. While the measures will be broadly welcomed, some observers will want to know how much of the money is new. The documents also suggest that No 10 wants to cut the number of teaching assistants.

The shadow education secretary, Angela Rayner, said: “Time after time, Boris Johnson has backed Tory cuts to school budgets that created the crisis in our classrooms, while slashing taxes for the richest. Johnson shows no sign of taking the action needed to undo that damage, and isn’t even proposing to reverse the Conservatives’ cuts to schools since 2010.

“It is concerning that this leaked document shows senior Tories casting doubt on the value of teaching assistants and suggesting that more cuts are on the way, despite the vital work they do, such as supporting children with special education needs.

“The next Labour government will fully reverse Tory cuts to our schools, increasing per pupil funding in real terms and offering a real terms pay rise to both teachers and support staff.”

Moran largely agreed, saying: “Schools will await this announcement with a mixture of expectation and dread. They had already been promised more funding in the final days of Theresa May’s premiership, only to see the money disappear in a puff of smoke. This time, Boris Johnson must put his money where his mouth is.

“Headteachers will be desperate to know what this means for frontline budgets meanwhile, the Conservatives’ ideological obsession with academies will continue. Schools will waste thousands of pounds being forced against their will to convert to a new structure that will do nothing to improve pupils’ life chances.”

The Labour MP, Bill Esterson, tweeted: