A 46-year-old man was arrested on Monday afternoon and is currently in custody, Sussex Police said.
A 46-year-old man has been arrested on suspicion of arson with intent to endanger life after a suspected arson attack at a mosque.
Emergency services were called to the building in Peacehaven in East Sussex at about 9.50pm on Saturday.
Sussex Police previously released images of two balaclava-clad people seen approaching the front door, before spraying suspected accelerant on the entrance to the mosque in Phyllis Avenue and igniting a fire.
Emergency crews from Sussex Police and East Sussex Fire and Rescue Service extinguished the blaze.
Those inside at the time were not injured, but significant damage was caused to the mosque and a nearby vehicle, the force added.
A 46-year-old man was arrested on Monday afternoon and is currently in custody, it said.
Detective Chief Inspector Mark Cullimore from the Surrey and Sussex Major Crime Team said: “The investigation is progressing at pace, and we are pursuing all lines of inquiry to identify those responsible for this appalling and reckless attack.
“We are continuing to appeal for information from the public in relation to the incident. If you have any knowledge, no matter how small you think it might be, we urge you to contact us immediately by calling 999, quoting Operation Spey.”
Superintendent Rachel Swinney said: “We acknowledge the serious distress and concern this has caused in our communities.
“There is an increased police presence at the scene and additional patrols taking place at places of worship across Sussex to provide visibility and reassurance.
“We will continue to engage with our religious communities to support them and ensure their concerns are heard and acted upon.”
