Writing standards among seven-year-olds in England have fallen for the second year in a row, the latest figures show.
Children sit tests in school at seven, 11 and 14
Some 80% of children reached Level 2 in school writing tests - a fall of one percentage point on 2006.
There was no change in maths, science or reading this year, with some 90% achieving the required level in maths, 89% in science and 84% in reading.
Schools minister Andrew Adonis said he was pleased with the results but called for more efforts to drive up standards.
He congratulated pupils and teachers for their hard work.
He added: "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.
"While there has been real progress over the last 10 years, we need to continue to push for year-on-year improvement because it is vital that all children gain a thorough understanding of the basics.
"That is why we are doing much more to support early reading, writing and maths."
In all subjects a higher proportion of girls than boys reached the expected level.
In writing particularly, girls were further ahead with 86% achieving the writing standard compared to 75% of boys.
And among seven-year-old boys, 84% were judged to be on track in speaking and listening, while girls were ahead with 90%.
Lord Adonis said that from September phonics would be central to the teaching of early reading for all children.
Six-year-olds with severe literacy difficulties are set to get extra, daily help with reading under the Every Child a Reader programme being rolled out across England between now and 2011.
So far a pilot of the programme has helped 5,000 seven-year-olds with difficulties.
But Lord Adonis rejected suggestions that the government had been slow to help children with extra reading and writing needs, saying that literacy was the core of what primary schools did.
"It isn't the case that every child isn't getting what they need to succeed. What we are doing is looking at how we can have still more improvement."
Liberal Democrat education spokesman David Laws said it was a national disgrace that "one in four boys don't even have the most basic writing skills aged seven.
"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."
Shadow schools minister Nick Gibb said the results revealed a lack of progress in raising standards in the "three Rs" which was "hugely concerning".
National Union of Teachers general secretary Steve Sinnott said: "Critics will seek to find fault but the results show that schools have sustained very high standards over time."
But he added that Lord Adonis should recognised that phonics has always been central to the teaching of reading.