The Prison Service says there has also been a disturbance at Rye Hill Prison, near Rugby in Warwickshire, but it was unrelated to the Maidstone Prison incident.
"There was a passive demonstration at HMP Rye Hill where around 60 offenders refused to return to their cells," she said.
"This was peacefully resolved within a few hours."
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The chancellor now faces the prospect of forming a minority government or calling for a snap election.
The 73-year-old said a return is unlikely "given the politicised atmosphere that seems to have afflicted our set."
Chancellor Philip Hammond said the UK will make a financial proposal to the EU in the next three-and-a-half weeks.