Firefighters from Atherton Fire Station attended the blaze at Charleston Court on Charles Street, Tyldesley, at just before 8.30am this morning.
A joint investigation into the cause is taking place by Greater Manchester Police and Greater Manchester Fire and Rescue Service.
The flat was ‘severely damaged’, but no one was injured in the fire.
Watch Manager Steve Green at Atherton said: “We had a building fire, a flat fire at Charleston Court on Charles Street in Tyldesley.
“It originally came through as a building fire but was made into a persons incident.
“At the moment the cause is being investigated by the fire investigations and Greater Manchester Police.”
He continued: “Nobody was injured. It turned out the occupant wasn’t at home at the time.
“We weren’t sure if they were in, so that’s why it was made a person’s incident.
“There was severe fire and smoke damage throughout the whole flat.
“We attended at 8.24am today.”