Serious assaults in prison 'at highest level for ten years'
Serious assaults in prisons in England and Wales reached their highest level for at least ten years, figures from the Ministry of Justice show.
There were 1,958 in the year to September 2014, including 431 on prison staff, statistics show.
There were also a record 170 sexual assaults in England and Wales' prisons in 2013.
BBC correspondent Danny Shaw said prison inspectors believed population and staffing pressures contributed.
They also said the impact of so-called legal highs had an effect, our home affairs correspondent added.
The number of serious assaults was up by nearly a third on the previous year, when 1,497 were recorded. The vast majority - some 1,920 - were in male prisons. Only 38 took place in female establishments.
Overall attacks on prison staff also increased, the figures show. A total of 3,470 were recorded over the 12 month period.
Prisons minister Andrew Selous said the rise was "unacceptable".
He added: "There is growing evidence that the increased smuggling of new synthetic drugs into prisons is a major factor in this. We have already announced a series of measures to crack down on this and will ensure that governors have the powers and support they need to tackle it."
He added: "Considerable work is already under way to develop our wider violence reduction strategy, led by an experienced prison governor, to address violence at its root cause."
Frances Crook, chief executive of the Howard League for Penal Reform, said: "The Howard League has been saying for some time that there is a crisis in our prisons and all we have received in return from ministers is disparagement.
"Yet the statistics released today confirm that violence and sexual assaults are at an all-time high."
She added: "We cannot simply cram more and more people into ever more overstretched prisons without a thought to the consequences."