A staffing boost launched to help tackle the jail safety crisis is just over half way towards its target, according to new figures.
From October 2016 to August 2017 there has been a net increase of 1,290 new prison officers, the Ministry of Justice said.
A further 872 personnel are expected to have started their training by January 2018.
Ministers have committed to bringing in 2,500 additional officers by the end of next year.
The recruitment drive forms part of the Government's response to surging levels of violence and self-harm that have affected much of the prisons estate in England and Wales.
Prisons Minister Sam Gyimah said: "We are taking unprecedented action to improve the safety in our prisons and the additional 2,500 prison officers are a key measure in creating calm and ordered environments.
"I have met prison officers across the country and am continually impressed by the work they do to manage prisoners day in and day out, to keep our prisons and the public safe.
"Bringing in these additional officers is critical to achieving safe regimes and I am committed to building on these figures."
Staffing levels have repeatedly been highlighted by campaigners amid a string of critical inspection reports and alarming statistics.
The most recent full prison workforce figures show that at the end of June there were 18,755 "full-time equivalent" staff in frontline roles.
This was the highest number in post since September 2013, but down on the level of close to 25,000 seen in the early part of the decade.
The number of full-time equivalent officers in key operational grades was at 19,219 as at the end of August this year.