A government investigation has been launched into the decision of a cash-strapped council to close 21 libraries.
Northamptonshire County Council voted through the closures as part of £40m of budget cuts.
Culture Secretary Matt Hancock said the probe was the result of concerns raised by the Chartered Institute for Library and Information Professionals (CILIP).
A council spokesman said the authority had held a 12-week consultation before making the closures.
It said government commissioners should be sent in to the council in the short term, with two unitary authorities eventually created in Northamptonshire.
The authority had originally consulted on three options for library services, the most severe of which would have seen up to 28 libraries closed.
Those plans were dropped in a final proposed budget which included £29.3m of savings, but gave library services a year-long stay of execution.
However, auditor KPMG then issued a legal warning saying the council's original budget was unlawful and its financial plans did not add up.
As a result, the authority voted to approve cuts of £39.2m including shutting 21 libraries, freezing staff pay and removing all bus subsidies.
In a letter to acting council leader Matthew Golby, Mr Hancock said he would "consider the complaint fully" to see whether a local inquiry - to be run by an independent assessor - is needed.
The letter said CILIP had raised concerns the council would no longer be able to provide a "comprehensive and efficient library service", had "failed to consult" on the decision and that the option voted for "was not the same option as in the public consultation".
A county council spokesman said a review of the library service "was a necessary element" of the budget-setting process, adding the authority had received feedback from more than 5,000 people.
A spokesman for CILIP said they welcomed Mr Hancock's decision "to intervene" after the council's "failure to provide decent library services".
He added: "We call on the council to stop any plans to reduce library services until the outcome of this intervention is known.
"The residents of Northamptonshire do not deserve to lose public libraries while their council is in chaos."