A Mississippi martial arts instructor was charged on Saturday with attempting to use a biological weapon after a ricin-laced letter was sent to President Barack Obama earlier this month, the US Department of Justice said.

Everett Dutschke, 41, was arrested at his Tupelo home shortly after midnight by FBI agents following searches of the residence and a former business as part of the ricin letter investigation.

He was later charged with "developing ... and possessing" ricin and "attempting" to use it "as a weapon", according to a joint statement by the US attorney for the northern district of Mississippi and the head of the FBI's Mississippi office.