The move follows rising concern about the training body’s performance among the NFB’s Major Contractors Group which represents firms with a turnover of £40m+.

The NFB has flagged the cost of operating the CITB as training programmes are cut.

The letter also calls for reform of a system where “levy is collected from micro, small and medium sized business and redistributed through grant expenditure to large businesses.”

The CITB is due to face its triennial consensus vote this year to guarantee its future.

The NFB was one of a host of trade bodies who backed the CITB at the last vote in 2017 in return for promised reforms.

Nick Sangwin, Chair of the National Federation of Builders said: “At the last consensus CITB were put on notice and we listened and gave them our approval.

“Many members feel that they haven’t listened to what we were telling them three years ago.

“With increasing bureaucracy in accessing training funding, reduced levels of local training, swathing suspensions and cuts to funded projects and programmes; CITB needs a fundamental shake-up and should ask industry to approve a new way forward.”

Stephen Radley, Director of Policy and Strategy at CITB, said: “Today’s comments show that we need to work better with NFB and its members.

“In the next two weeks, we will share our plans on the levy and how we will support the industry this year.

“We will use this to work more closely with NFB and other stakeholders.

“Our plan will focus on simple practical support on apprenticeships and training, building on what we’ve already done during the crisis.

“Since that hit, we’ve suspended levy bills, brought forward apprenticeship grant payments, supported online training and broadened the scope of grant support for small and medium-sized employers.

“Feedback from thousands of construction employers suggests that this support has hit the mark.

“We’ve also accepted NFB’s previous recommendations for reform, with small firms represented on our Board and on the Nations Councils we’ve set up.

“We’ve reduced our headcount from 1,500 to 833 with a further reduction of 190 to come, together with other measures to reduce costs. And we will press on with plans to increase efficiency this year.”

Herman Kok, Company Secretary of the Lindum Group, added: “I have chaired a Lincolnshire CITB funded training group for 18+ years.

“It saddens me that CITB appears to have completely lost its way.

“No support for Health and Safety training, no support for companies of our size and no support for (small) local training companies and still CITB insists on levying our industry at the start of what is likely to be one of the worst recessions in living memory.

“A topsy-turvy world: Instead of CITB supporting us, our industry is asked to support the CITB! And for what?”