The number of schools in England judged to be failing has risen by 5% since last term, education inspectors say.
Some 1% of schools are judged to be failing
By the end of March this year, 256 schools were in "special measures" compared to just 243 at the end of December - a rise of 13 schools.
Ofsted said the rise was partly because there were fewer schools in a position to be removed from this category.
Schools in special measures can be closed if they do not improve fast enough. Just 1% are in this category.
By the end of the spring term, 179 primary schools were in special measures, eight more than at the end of December.
Four more secondaries were in special measures, taking the total to 52, with one more special needs school also in the failing category.
Eleven special schools were judged to be failing, up one from December.
The rest were pupil referral units - 14 of which were judged to be failing.
A spokeswoman for Ofsted said: "The number of schools removed from special measures in the spring term 2007 was lower than in previous terms because very few schools were made subject to special measures in the spring and summer terms 2005.
"It normally takes around two years for schools to improve sufficiently to be removed from special measures."
However the most recent increase follows a rise of 16.8% - or 35 schools - from 208 at the end of August 2006 to 243 at the end of December.
Schools Minister Jim Knight said the government had halved the number of failing schools since 1997-1998.
He also highlighted the fact that the figures show that compared with last term overall there are fewer schools in categories of concern.
Until August 2005 categories of concern were those in special measures, with serious weakness, underachieving schools and secondary schools with inadequate sixth forms.
From September 2005 these categories changed to those in special measures and those requiring significant improvement.
Mr Knight added: "This is a promising trend despite the fact we raised the bar on inspection in autumn 2005.
"The new, tougher inspection framework means there is no room for 'coasting schools'.
"Schools that used to escape closer attention may now find themselves in special measures.
"Our reforms to tackle failing schools demand radical action from the school and the local authority to turn the school around quickly."
Shadow education secretary David Willetts said the figures were more evidence of the "pressing need" to focus on raising standards in state schools.
"It demonstrates why it is right to concentrate on creating more good schools so we can improve opportunities for all pupils, particularly those from poorer backgrounds, who are currently being failed by the system," he added.
Liberal Democrat education spokeswoman Sarah Teather said the government was running out of excuses for its inability to deal with failing schools.
She added that schools with more underachieving pupils should be given extra funds so they have the resources to deal with those pupils' additional needs.