Travellers have moved into a car park in Stowmarket, opposite the town's Asda store.
A local resident said he understood the caravans had arrived in the town-centre car park early on Friday.
The car park, on Iliffe Way, is operated by Mid Suffolk Council and is used by long-stay visitors to the Museum of East Anglian Life.
It is a pay and display car park and also has a recycling centre for bottles, cans and paper.
A spokesman for Asda in Stowmarket said the store had contacted the council about the travellers and they had also made Asda's head office aware of the situation.
Travellers previously moved on to the same piece of land during July 2015.
A spokesman for Mid Suffolk District Council said: "We are aware of a number of caravans and vehicles stopping at the car park on Iliffe Way in Stowmarket this weekend.
"We are liaising with the travellers, including providing facilities to dispose of their waste safety, and keeping local councillors informed. We are following normal procedures for dealing with unauthorised encampments."
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