A Ugandan national was on the night of Monday arrested by police officers on patrol in Teso South, Busia County.
A police report said the man was riding on a bike with two others at around 10.30pm when they were stopped by the officers.
The three, police said, defied an order to stop and sped off; the officers gave chase and cornered one pillion passenger identified as Chandi John who hails from Tororo, Uganda.
Upon a thorough frisking, police officers discovered that the elderly man had stashed in an AK-47 inside his pants.
The gun which did not have a visible serial number had 30 rounds of ammunition.
It is not clear where the suspect and his accomplices were headed during the arrest.