Nottinghamshire Police would like to speak to two men seen near a Worksop gym before it was gutted by fire.
New images show the extent of internal damage after Unique Fitness on Ryton Street was destroyed in a blaze.
Firefighters were called just before 3am on Monday, February 13 and around six crews from Nottinghamshire Fire and Rescue attended and have been working with Bassetlaw District Council to make the building safe.
Officers are now treating the fire as arson and are appealing to anyone who saw anything suspicious in the area at the time.
A spokesperson said: "We are particularly keen to speak to two slim built men seen wearing dark clothing and carrying what looked like a holdall at around 2.55am on Newcastle Street.
"If you have any information that could help, please contact Nottinghamshire Police on 101 quoting incident 61 of 13 February."
The shocked owner of the gym, Stephen Ashmore said the business was due to open next week after a refurb.
Stephen said: “A lot of work had gone into that gym.
“It was a community effort with many electricians and decorators doing the work for free. A lot of people wanted it open. I’m not sure what to do now.”