He is described as white, in his 30s or 40s, with short dark hair and dark facial hair.
The force said he was wearing blue jeans and a dark green jacket with a white stripe on both sleeves.
Ch Insp Nick Paling, Great Yarmouth’s district commander, said: “We recognise how shocking and distressing these incidents are for the victims, their families, and the wider community.
“Specialist officers have been deployed to support both girls as we work through this investigation.”
