Children's education and mental health is at risk of being harmed by "high-stakes" testing which is used to hold primary schools to account, a cross party committee of MPs has warned.
The close links between school performance and national curriculum tests, known as SATs, can have a negative impact, with pupils taught a narrower curriculum, and staff simply teaching pupils to pass the tests, according to a new report by the Commons education committee.
It calls for a major overhaul of annual league tables, with a new system introduced that shows a school's results over a three-year average, instead of one year.
Committee chairman Neil Carmichael said that while schools need to be held accountable for children's progress and achievement, action is needed to lower the stakes.
The report, which comes the week before pupils across England sit the tests, warns: "Assessment is closely linked to the accountability system in primary schools, with Key Stage 2 results used to hold schools and teachers to account on the progress and attainment of pupils.
"However, the high stakes system can negatively impact teaching and learning, leading to narrowing of the curriculum and 'teaching to the test', as well as affecting teacher and pupil wellbeing."
It adds: "The stakes should be lowered at primary school in order to combat some of these negative impacts.
"Performance tables should include a rolling three-year average of Key Stage 2 attainment and progress data to reduce the focus on an individual year's results."
The committee also suggests that Ofsted should not focus too heavily on SATs when inspecting schools.
Last year pupils sat tougher papers based on a new national curriculum, and 53% of pupils reached the new expected standard in reading, writing and maths.
The year before, under the old system, 80% achieved Level 4 or above in these core subject. Ministers were at pains to stress that the results were not comparable.
But union leaders branded the 2016 results a "shambles".
In its report, the committee said: "The Standards and Testing Agency did not oversee the implementation of the new assessment system in 2016 effectively, with guidance delayed and test papers leaked online.
"This caused significant disruption in primary schools as schools felt there was too little time to implement effective new assessment systems and prepare teachers and pupils for SATs."
Mr Carmichael said: "Many of the negative effects of assessment in primary schools are caused by the use of results in the accountability system rather than the assessment system itself.
"The resulting high-stakes system has led to a narrowing of the curriculum with a focus on English and maths at the expense of other subjects like science, humanities and the arts.
"It is right that schools are held to account for their performance but the Government should act to lower the stakes and help teachers to deliver a broad, balanced, and fulfilling curriculum for primary school children."
Russell Hobby, general secretary of the National Association of Head Teachers said that last year's tests were "a mess of chaos and confusion".
"Add in to this the high stakes nature of the system for school leaders, and you get a toxic mix."
He added: "The Committee's call to scrap the publication of results from a single cohort, proposing instead a rolling three year average of Key Stage 2 results, is therefore very welcome. Data is useful, but it is important to recognise its limitations."
A Department for Education spokeswoman said: "We will consider the recommendations of this report carefully and respond in due course. A consultation relating to primary assessment is ongoing."
She added that the department has committed to introducing no new tests before 2018/19.