Nick Blackwell has been admitted to hospital with what is believed to be a bleed on the brain.
The 25-year-old sustained the supposed injury during his fight against Chris Eubank Jr in London last night.
The referee stopped the bout in round 10 on medical advice and Blackwell was later taken from the ring on a stretcher.
Subsequent reports have claimed that the middleweight has been placed in an induced coma while doctors carry out an assortment of tests.
"It is our understanding that Nick has a bleed on the brain and is under observation by hospital staff," said British Boxing Board of Control general secretary Robert Smith.
A statement from Blackwell's camp is expected to be released in the near future.