Some six caravans have pitched up at the former Camper UK premises on Station Road in North Hykeham.
The caravans arrived some time on Sunday, September 21, and have been there overnight.
The premises were empty after Camper UK moved to a new building on Deacon Road earlier this year.
North Kesteven District Council said it cannot investigate until the owners of the private stretch of land require their assistance.
Lincolnshire County Council, which works with district authorities on unauthorised campers, are not getting involved at this stage either.
Lincolnshire Police are aware and monitoring the unauthorised camp, but have no police action planned at this stage.