Millward, a Green Party councillor, said: “We think the level of misinformation and lack of communication has led to fear and the risk of unrest.”
She added that councillors took the view that having people in such intensive numbers on one site was “not a good way to accommodate people” and brought “far greater risks”.
At the meeting, councillors heard the average stay at the camp would be about 70 days.
The Home Office confirmed the arrangement with the Ministry of Defence was the camp would be used for a maximum of 12 months.
Millward said councillors pushed the Home Office on communications, adding it was a matter of public safety.
She said the Home Office needed to explain the plans to parents and other groups, including women and children, adding: “There’s an awful lot of anxiety and concern for safety and for wellbeing.”