The Government has sacked the mental health champion for schools, who criticised the rigorous testing culture young people face as detrimental to mental health - but denies the two things are connected.
Natasha Devon was appointed to the role last August and also voiced concern about anxiety caused to students by debt.
The Department for Education (DfE) strongly denied the axing of the role was politically motivated in order to silence criticism.
Devon used a headteachers' conference in London last week to warn about the level of mental strain being put on pupils.
"Time and time again over recent years, young people - and the people who teach them - have spoken out about how a rigorous culture of testing and academic pressure is detrimental to their mental health," she said.
"At one end of the scale we've got four-year-olds being tested, at the other end of the scale we've got teenagers leaving school and facing the prospect of leaving university with record amounts of debt.
"Anxiety is the fastest growing illness in under-21s. These things are not a coincidence."
The DfE said that as a new cross-government mental health champion was being appointed, Devon's role had been superseded.
The department stressed the new role had been recommended in February by an independent task force, and Devon's position was being dropped to avoid "confusion".
An Education Department spokeswoman said: "Natasha has done a great job of helping us to raise the profile of young people's mental health since her appointment last year.
"Since that time, the independent NHS task force report has been published which recommended that a cross-government mental health champion be created - for this reason we have had to reconsider the department's own role.
"We have asked Natasha and others who have been involved in our work to empower schools and young people to promote good mental health, to continue to work with us as we prepare to launch our activity later this year."
Devon told the Guardian: "I can confirm that I am no longer authorised to comment as the Government's mental health champion for schools.
"The DfE have extended an opportunity for me to continue working on the peer-to-peer project they were seeking my advice on."
Devon said she was in talks regarding the new role, adding: "Either way I'm not going anywhere and will continue to campaign for the rights of young people and those who teach them."
Sarah Brennan, chief executive of YoungMinds, said: "We are very surprised and sad that Natasha's role as mental health champion has ended.
"She's done a superb job of drawing attention to the crucial importance of mental health and well-being in schools."
The level of testing in schools led to a day of protest this week as parents were encouraged to keep children home from schools to highlight concerns.