The inquiry set up by David Blunkett, the Secretary of State for Education, also found that national tests for 11-year-olds were among the most rigorous and reliable exams in the world. But some questions in the tests were still unclear.
Reports said that the pass mark was secretly lowered so that national targets would be more easily met in 2002.
But an independent panel of education specialists said that measures to uphold test standards were "in advance of many, if not all of our international counterparts" and more thorough than those used in GCSE and A-level exams.
The report said it could find no evidence that anyone, "let alone Ministers or officials at the Department for Education, sought to influence the tests or the arrangements governing them, in order to meet national targets".
The panel, chaired by Jim Rose, director of inspections at the Office for Standards in Education, also said it was surprised to find "unclear illustrations and some ambiguous wording".
A caption under a picture of a spider said that "finally, the spider spirals back into the centre.
The web is then ready for the spider to catch its prey." But the comprehension passage about the spider said that "after finishing its web the spider usually waits out of sight".
Candidates were asked where the spider lay in wait for its prey. Three- quarters gave the right answer - out of sight - but one-quarter said it waited in the centre of the web.
Mr Rose said: "It is little things like that that need acute vigilance but it is still a very reliable test."