Braddan Commissioners chair Andrew Jessopp says the Department of Health and Social Care needs to prove hospital roads aren't public rights of way.
He says the authority is losing £1,000 a day because it can't issue leases for the Roundhouse.
And he added legal action could be taken if leases are handed out while there are still problems:
In response, the Department of Health and Social Care says it supports the project, but won't compromise the safety of patients and the emergency services.
It adds sharing the current roads isn't suitable and is banning vehicles from the site from March 4.
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