Ambulance services were called to Lang Street in the city around 5pm on Friday, with the Scottish Fire and Rescue Service dispatching six units to the scene of the accident.
According to the police, the body of a man was found in the apartment.
A police spokesman said: “At around 5pm on Friday 18 August we were called to a fire at a flat on Lang Street in Paisley.
“Emergency services were at the scene and the body of a man was found inside.
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“Investigations are ongoing to officially identify him and determine the cause of the fire.
“The road closures on Lang Street and Violet Street remain in place.”
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Road closures imposed on Lang Street and Violet Street remain in place, police said.