A joint investigation is under way after an elderly woman died in a house fire in the Mumbles area of Swansea on Monday morning.

Fire crews found the 87-year-old in an upstairs bedroom in Castle Avenue, after the blaze was discovered by police.

Firefighters said the fire broke out in the first floor and loft areas.

A South Wales Police spokesman revealed the incident was not being treated as suspicious.

"Police discovered the fire at 0230 GMT and the scene has been examined by forensic fire officers and scenes-of-crime officers," said Detective Inspector Dale Pointing from Swansea Central station.

"At present, we are not sure what the cause of the fire was, but we are not treating it as suspicious."

The investigation is being carried out jointly by South Wales Police and the Mid and West Wales Fire Service.

Dyfrig Williams, Divisional Officer for the Mid and West Wales Fire Service said two appliances attended the blaze.

"The premises were well alight and fire had broken into the roof void," he said.

"Four firefighters made entry into the house with breathing apparatus to fight the fire and located the occupant.

"The body was found in the bedroom on the first floor," he added.