The new National Assessment Agency, which will take over the administration of tests at key stages 1, 2 and 3, will also work with examining boards to modernise the way 24 million scripts for GCSE and A-level are marked every year. Electronic scanning of scripts will be tried out and examiners will be offered higher fees to attract more of them.
The changes leave the QCA acting as a regulator to maintain standards. A spokesman said: "The new agency will operate as a subsidiary of the QCA, and its accountability will remain with the QCA.
"This is a step forward and allows the QCA to get involved in more logistical issues, where there have been a lot of problems.
"There will be a more streamlined service to schools."
But John Bangs, head of education at the National Union of Teachers, said:
"We have been here before with the old School Curriculum and Assessment Authority and the National Curriculum Council.
"I have yet to be convinced that separating assessment from the curriculum has anything to recommend it. I cannot see it working or why it should should have been stripped out of QCA responsibility.
"The QCA has a good working relationships with its partners including the teacher associations and freeing it from assessment will have led to the same old organisational disputes we had in the days of SCAA and the NCC."
However, John Dunford, general secretary of the Secondary Heads Association, said he was pleased with the development.
He said: "The division between the roles of the test operator and regulator are to be welcomed.
"QCA will be able to do a better job as a regulator if it is not setting and marking tests."
Tim Yeo, the shadow education secretary, said the Government should have spent the money on making the QCA "institutionally independent" to stop annual allegations of dumbing down of exams, rather than creating a new quango.