The FBI offered a $5,000 (Dh18,000) reward for information leading to the arrest of anyone connected to a fire that badly damaged an Islamic centre in south-eastern Missouri and coincided with the start of Ramadan.
Richard Quinn, the special agent in charge of the FBI's St Louis Division, announced the offer on Friday, hours after the fire broke out at the Islamic Centre of Cape Girardeau.
Up to 15 people fled from the building and escaped injury. Cape Girardeau fire chief Travis Hollis said the damage to the centre was extensive.
The Missouri chapter of the Council on American-Islamic Relations, a Muslim advocacy group, said the fire began at the front door of the building.
The group suggested the blaze was set deliberately to coincide with the start of the holy month.
"Because the fire was deemed 'suspicious', and because it occurred at a house of worship on a significant religious date, we urge law enforcement authorities to investigate a possible bias motive for the blaze," the group's national communications director, Ibrahim Hooper, said.
The Bureau of Alcohol, Tobacco and Firearms and the state fire marshal also are investigating the blaze.
Cape Girardeau is about 190 kilometres south of St Louis.
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