The House of Commons public accounts committee is particularly critical of the government's 2015 Future in Mind strategy, which is backed by £1.4bn in funding and pledges "a cross-departmental vision" for improving mental health services by 2020.
A committee report published today on mental health services for children and young people says the government has "no comprehensive, long-term plan for how it will fulfil its commitment to implement Future in Mind".
"The government is committed to delivering the cross-departmental vision set out in Future in Mind but has not set out the actions and budget required to deliver it in full, or any measurable objectives or targets," states the committee's report.
"In practice a number of separate work programmes, largely NHS-led, are implementing parts of Future in Mind. There are no cross-departmental accountability arrangements in place for delivering it, or for children and young people's mental health support more generally."
MPs are calling on the Department of Health and Social Care (DHSC) to take the lead on developing a "comprehensive, practical and long-term cross department plan" that clearly sets out the responsibilities for each government department in improving support.
A lack of progress in boosting the number of mental health staff needed to offer support is another concern raised by the committee.
Between March 2015, when Future in Mind was published, and September 2017, there has been just a one per cent increase in the overall mental health workforce.
Factors behind this slow progress include the removal of the bursary for student nurses, rising cost of living and continuing professional development cuts, says the report.
Another concern raised is the lack of clarity over the government's policy of creating "parity of esteem" between mental and physical health services.
"The NHS has committed to achieving ‘parity of esteem' between mental and physical health services, but has not defined what the practical, meaningful outcomes are in terms of access to services, waiting times, or patient outcomes," states the report.
"For example, it has not yet determined what percentage of young people in need would access mental health services under full ‘parity'."
Earlier this month, NHS England published the NHS Long Term Plan which promises to help 345,000 more young people with mental health problems through community-based services, including schools and colleges.
Committee chair Meg Hillier said the committee "will be keeping a close eye" on the plan's progress.
"Children and young people with mental health conditions are being failed by the NHS. Provision is far below required levels and many people who do get help face long waits for treatment," she said.
"This can be devastating for people's life chances; their physical health, education and work prospects.
"The NHS must accelerate efforts to ensure it has the right staff with the right skills in the right places. But there is a broader role for government in better supporting children and young people.
"Effective action on prevention and early intervention can help young people more quickly, as well as relieve pressures on health services."
The report also details recent figures that show that only 30 per cent of children and young people with a mental health condition received NHS treatment in 2017/18 "and many more faced unacceptably long waits for treatment".
In addition, the committee echoes concerns raised by the House of Commons education committee in May last year over government plans to boost mental health support in schools.
Committee members are also concerned that the plans, announced in a green paper in 2017, will only cover a quarter of the country by 2022/23.
Kadra Abdinasir, strategic lead for the Children and Young People's Mental Health Coalition backs the committee's concerns.
"We particularly welcome the committee's recommendation that government takes a cross-departmental and long-term approach to truly transform services and place prevention and early intervention at the heart of these initiatives," she said.
Kevin Courtney, joint general secretary of the National Education Union, says the report "presents a damning picture of the current state of mental health provision for children and young people across the country".
"Schools are witnessing the devastating impact this has on their pupils on an ever-increasing basis," he added.
A DHSC spokeswoman said: "The mental health of our children and young people is a key priority for this government. As part of the NHS Long Term Plan, we have committed to increasing the funding for children and young people's mental health services faster than both overall NHS funding and total mental health spending.
"This will give 345,000 more children and young people access to NHS-funded mental health services and support in schools and colleges, will ensure young adults receive better support until the age of 25, and that crisis care is provided through NHS 111, 24 hours a day, seven days a week.
"New NHS roles and careers are being shaped to reflect the future needs of all the priorities set out in the Long Term Plan for the NHS."