Warning letters have been sent to 14 families suspected of unlawfully living on a holiday park.
Mid Suffolk District Council sent 'planning contravention notices' to the residents at Stonham Barns this week - and has followed up with visits from its housing team.
The recipients have been given 21 days to answer questions about their residential status or face a possible £1,000 fine.
The council said its housing officers would be available to help or offer support to anyone facing difficulties as a result of the request - but it needed to address community concerns about the unlawful occupation of units.
Authorities first became aware of problems on the site in late 2018, when many residents, including some with serious health conditions, were found to have no other permanent home.
Some said they had been living on site permanently for years and had nowhere else to go.
MSDC said it wanted to work with the park - but in July last year decided to take enforcement action against its owners, saying "discussions had failed".
MORE: Holiday park to be prosecuted over tenants staying on site all year round
Since then, some of the residents have moved out.
The council said it had been working to identify those who had nowhere else to live and give them support.
The 14 households which received letters this week are the final few MSDC still believes are living on site permanently.
However Stonham Aspal Parish Council, which has been involved in discussions with MSDC and the holiday park, has raised doubt about the number of homes.
Council chairman Peter Emberson said: "We believe there are over 100 people still living on the site and we are asking MSDC to continue their investigations to ensure Stonham Barns is used only as a holiday park, not turned into a residential caravan estate.
"I urge anyone living on the site to speak to MSDC before they are forced to leave."
The two councils and Stonham Barns have been holding regular meetings.
At the latest meeting, Mr Emberson called on Stonham Barns to make it clear in its advertising that people could not live on site.
Stonham Barns owner Alan Forward was quoted as saying he didn't want anyone living on site as it was "bad for business".
Stonham Barns did not respond to a request for comment - but previously said it would work with MSDC to resolve breaches.
Council says it is on hand to help residents
Mid Suffolk District Council said its action was in response to concerns about the unlawful occupation of the holiday park units.
It said it had been in discussions with the owner to ensure Stonham Barns operates as a holiday park, not a residential park.
"We believe this is consistent with our approach to encouraging our tourism economy of the district and ensuring our communities can be confident that sites with planning permission are being used as they and we expect," a spokesman added.
"Letters have been sent to 14 unit owners seeking some additional information about their particular circumstances and we are offering support to help those people clarify their situation."
The council said this was a "fact finding stage" to establish their residential status. It said anyone facing difficulties could talk to its housing teams "who are on hand to offer help or support wherever required."
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