Almost one in four primaries admitted they "taught to the tests" while fewer than half said it was possible to cover the curriculum satisfactorily in the teaching time allowed.
Only 47 per cent of schools said they had time to teach outside the national curriculum, a survey of nearly 400 primaries for the Qualifications and Curriculum Authority found.
Bill Boyle, director of Manchester University's Centre for Formative Assessment Studies, who has co-ordinated the annual QCA survey since 1995, said: "This was the first year we investigated how the national tests had affected the way the curriculum was delivered.
"It was very striking that the majority of schools reported it had changed their focus, with many practising past papers with children and incorporating revision time into the curriculum."
Teachers also said quality of teaching was being lost as they were forced to cover a wider curriculum in less depth.
Three out of five schools said geography had been the biggest loser in the competition for teaching time, while 60 per cent of teachers said five to seven-year-olds were losing out on time for art.
The QCA's secondary survey of more than 370 schools revealed that key stage 3 tests had had a similar impact on teaching strategy. Nearly nine out of 10 English, maths and science heads of department said that additional test preparation was now recognised as "a fact of life".
News 5 TESJnovember 27 1998 in brief jeff morgan