A woman questioned by police after a suspected explosive device was found at a restaurant in Hove has been released on bail pending further inquiries.
The 38-year-old was arrested on suspicion of arson with intent to endanger life and criminal damage.
The device was found on Tuesday by fire investigators called to an arson attack at Breakfast at Tiffany's, in Kingsway.
Police believe the lit object that caused the fire and the explosive device are connected.
The alarm was raised at 0015 GMT by a man who spotted flames as he drove past the restaurant.
The suspected explosive device was found later that morning when investigators returned to examine the scene in daylight.
Sussex Police cordoned off the area in Kingsway and evacuated nearby buildings while a bomb disposal team carried out a controlled explosion.
The force does not believe it was a random attack.