Concerns about a blueprint for where thousands of homes could be built in Norwich, Broadland and South Norfolk over the next two decades have been raised by Natural England.
Some 5,000 have already been built and the locations of around 74pc have been identified in previous plans.
But the plan outlines where the other homes could be acceptable.
The Greater Norwich Development Partnership is due, on Thursday, June 24, to agree to submit the plan to the secretary of state so it can be adopted.
But it has emerged there are issues which officers fear, if unresolved, threaten the chances of an inspector finding the plan to be sound.
At a meeting of Norwich City Council's sustainable development committee on Tuesday, Graham Nelson, City Hall's director of development and city services, revealed Natural England's concerns.
He said agreement had yet to be reached with Natural England over how adverse effects on protected habitat sites around Norwich would be avoided.
Work has been under way to create what would be a tax on developers to pay for mitigation measures, but that has yet to be adopted.
And agreement has yet to be reached on how Natural England would be able to spend that money.
He said: "That's a work in progress. It's not been signed or agreed as of yet and officers are of the view that unless we can tick that particular box and have reached that agreement, we should not submit the plan."
But he said he was optimistic it would end up being signed. The recommendation for Thursday's meeting to push ahead to submit it - subject to the agreement being reached.
Norwich, Broadland and South Norfolk councils would also have to individually agree the plan in the months ahead.
Green city councillor Denise Carlo said: "Four road schemes and the plan will concrete over really extensive, hundreds of acres of countryside around Norwich."
A further issue is the plan has not identified sufficient sites to meet the needs for accommodation for Gypsies and Travellers.
He said that would not render the plan unsound, but that it was likely an inspector would request further work.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here