Ten South Yorkshire firms have been banned from using their premises or only allowed limited access because of fire safety concerns over the last year.
Fire chiefs have expressed concern at the number of prohibition notices served since last April, with only six served over the previous two years.
Prohibition notices are served where the fire service considers that in the event of a fire the risk to people using a building is so serious that use of it should be prohibited or restricted.
Firms are only allowed full access again once steps have been made to resolve issues.
Continued use of a building after a notice is served can result in prosecution.
Technical fire safety manager Amy Jenkinson, of South Yorkshire Fire and Rescue, said: “Our aim is always to engage with local businesses in a positive way and to work with them to make improvements before we have to resort to closing part or all of a building, or resort to criminal prosecution.
“But the recent increase in the number of prohibition notices served is worrying and we’d urge business owners to take the time to learn about their responsibilities under fire safety legislation and complete a fire risk assessment to reduce the likelihood of suffering a serious incident which could put their business and their people in danger.”
South Yorkshire Fire and Rescue has tackled more than 500 fires in non-domestic properties in the last three years.
For more fire safety advice for businesses, visit www.syfire.gov.uk/business-advice