Police are investigating an incident involving three prisoners at HMP Full Sutton in Yorkshire.
A Ministry of Justice spokesman said: "An incident involving three prisoners took place at HMP Full Sutton on 26 May from 4.25pm and was successfully resolved at 8.40pm after staff intervened.
"A police investigation is ongoing."
More top news
The Olympic champion released a statement after a newspaper alleged his American coach may have broken anti-doping rules.
Storm Ewan gives a wet and windy end to the weekend across many northern and western areas.
The Home Secretary said the Government is "against cliff edges" and immigration figures will not suddenly fall when the UK leaves the EU.