Nick Blackwell was taken to hospital this week after falling ill following a sparring session.
The former British middleweight champion spent a week in a medically-induced coma earlier in the year after suffering a bleed on the brain following his fight with Chris Eubank Jnr in March.
Having since retired from fighting, Blackwell was issued with his trainer’s licence a month ago but is understood to have become unwell having risked taking part in a sparring session.
Speaking to The Sun, British Boxing Board general secretary Robert Smith said: “I understand he was sparring, fell ill, was taken to hospital and then underwent a procedure.
“I don’t know exactly what the procedure was, other than the fact they tried to relieve pressure on the brain and he’s now in a stable condition. That’s all I know.
“I’m sickened by it. It’s a very tough sport and the doctors here did a wonderful job to save his life. The doctors at hospital saved his life and kept him going.
“He made remarkable recovery and for somebody to go and do what he’s done, for what I thought was a very sensible young man, is just beyond belief.”
Dick Clerkin makes his GAA Hour debut to talk about a wonderful career and argue passionately with Colm Parkinson over Sky Sports GAA. Subscribe here on iTunes.