The level of basic skills among seven-year-olds has not noticeably improved in the past year, but the government insists high standards have been maintained.
Results from the national Key Stage 1 tests show pupils performed broadly inline with last year's results in science, reading, writing and maths.
The Liberal Democrats said the government had "lost momentum" in driving up improvements in primary schools.
However, the government defended the results, which measure performance among pupils at the beginning of junior school, saying they would continue to improve on existing standards.
Schools minister Andrew Adonis praised schools and teachers for helping the majority of primary school pupils reach the minimum standard.
Lord Adonis said: "We know that children who reach the expected level in reading, writing and maths at seven years old have a much better chance of leaving primary school with a solid foundation in literacy and numeracy skills.
"We must do more to raise standards even further, especially in writing."
Nine in ten children received level two or higher in mathematics, an improvement of six percentage points since 1997 but static since last year.
Results also remained constant in reading, with 84 per cent of seven-year-olds hitting the required standard, up four per cent since 1997.
Achievement in writing fell by one per cent this year, with one in five children failing to meet the required standards.
Nearly nine in ten hit the required target in science, contributing to a four per cent rise since 1997.
The figures mask the continuing performance gap between boys and girls, with male pupils consistently underperforming at age seven.
The Liberal Democrats said the writing skills of seven-year-old boys should be seen as a national disgrace, with one in four lacking "even the most basic" writing skills.
Schools spokesman David Laws said: "These figures will be very disappointing for ministers as boys continue to perform far worse than girls, and improvement overall has stalled or in some cases is even going backwards."
The Conservatives said the government had shown a "worrying lack of progress" in school standards.
Shadow schools minister Nick Gibb said the results were "hugely concerning" as the early years of school are the "critical building blocks" of a child's education.
Mr Gibb said: "Ministers are worryingly complacent about these figures; once again the government are being too easy on themselves. Until we get literacy and maths to significantly higher levels in the first two years of school we will continue to have problems later on in the education system."
The government insists it will do more. Children starting school this autumn will be taught reading via phonics and any child still struggling with their reading by age six will receive daily intensive tuition.
Primary teaching of maths is also under review and the government wants pupils to know their times-tables a year earlier than present targets demand.
Sir Jim Rose, author of the Rose Review which recommended every primary school adopt phonics, said: "There are no quick fixes that will raise standards overnight.
"However, all the indications are that settings and primary schools are taking serious account of the recommendations of the reading review and working very hard to secure excellent standards of literacy.
"These investments in high quality teaching will take time to make an impact on standards; nevertheless we should be optimistic because the looked for gains for children are being achieved by many schools and are within reach of the rest."
The Key Stage 1 results follow a study by researchers at Durham University, which found the government's varied initiatives and investments in early years education had not made a noticeable impact.