The A421 between Buckingham and Great Horwood has been closed for safety reasons because newly-laid road surfacing has failed.
A signed diversion has been put in place which takes traffic via the A422 to Stony Stratford and the A5 to Milton Keynes through Bletchley.
The road closure was put in place because reports that parts of the road were breaking-up.
An e-mail from Transport for Bucks seen by this newspaper reads: “Engineers are currently on site assessing remedial options, with the intention of re-opening the road during today in time for the evening rush hour.
“Note however, this cannot currently be guaranteed, and the road will remain closed for as long as necessary to ensure public safety.
“All areas of failure will be resurfaced overnight to ensure that traffic is able to operate normally on Tuesday.
“The reasons for the material failure are currently being investigated.”
More on this as we get it.