The number of violent or sex offenders charged with serious crimes while being monitored after they are released from prison has jumped by more than a quarter, new figures reveal.
In 2014/15, a total of 222 individuals under supervision were accused of committing a "serious further offence" (SFO) - an increase of 28% compared to the 174 in the previous year.
This category can include crimes such as murder, manslaughter or rape but the alleged further offences were not specified.
The data also revealed a jump in the rate of registered sex offenders being managed in the community, so that they now account for 98 per 100,000 head of population - or nearly one in every 1,000.
The figures, released by the Ministry of Justice (MoJ), relate to those who are subject to Multi-Agency Public Protection Arrangements (Mappa).
Under the system authorities are tasked with assessing and managing the risk posed by sexual and violent offenders.
As of March this year, there were 68,000 criminals subject to these arrangements, with nearly three quarters (73%) registered sexual offenders.
A bulletin published by the MoJ said that the increase in SFOs recorded in 2014/15 is almost entirely down to a rise in alleged re-offending by sex criminals.
It added: "Annual increases in the number of SFOs from 2010/11 to 2013/14 were broadly in line with increases in the number of MAPPA-eligible offenders over this period.
"Although the number of MAPPA-eligible offenders continued to increase between 2013/14 and 2014/15, the rise in the number of SFOs outpaced the rise in the MAPPA population in this period."
It comes days after an investigation by the BBC raised serious concerns about Mappa, with probation staff reportedly suggesting cases are not receiving sufficient scrutiny.
Tania Bassett, of the probation union NAPO, described the figures as "worrying" and suggested officers are increasingly stretched following privatisation.
She said: "It is quite a significant increase. One of the key things that came out of our AGM was that people's workloads are so high that they just don't have the time they used to have to reflect on Mappa cases.
"That, I think, is one of the factors."
The Ministry of Justice said less than 1% of Mappa-managed offenders go on to be charged with a SFO.
A spokeswoman added: "MAPPA manage some of the highest risk offenders once they have served their prison sentence. Serious further offences are rare but each one is taken extremely seriously and investigated to make sure the right lessons are learned.
"A recent report by the independent Probation and Police Inspectorates found improvements had been made to MAPPA over the last four years."
Meanwhile the Government seized on separate data on overall re-offending rates as evidence for the need to overhaul the prison system.
They showed that nearly half of all criminals (45.8%) commit new offences within a year of being released. Some 125,219 crimes were perpetrated by inmates in the 12 months after they were freed in 2013.
Prisons Minister Andrew Selous said: "These shocking figures show why our reforms are so important.
"We cannot put up with a situation where so many prisoners commit yet more crime, and cause yet more misery to victims, almost as soon as they are released.
"We are determined to provide prisoners with education, work and an opportunity to redeem themselves. That way we can cut crime and better protect the public."