Police are investigating how a fire started at a basement flat in Telscombe Cliffs in the early hours of this morning (Wednesday April 10).
Forensic examinations are underway at the property in Telscombe Cliffs Way and officers are appealing for anyone with information to come forward.
East Sussex Fire and Rescue Service were called to the scene and extinguished the blaze by 1.55am.
Sussex Police said there were no occupants in the flat at the time of the incident.
Officers said they were grateful to the other residents of the building for their cooperation.
If you saw or heard any suspicious activity at around 1am this morning call police on 101 quoting serial 47 of 10/4.
Alternatively leave an anonymous message with the independent charity Crimestoppers on 0800 555 111.