A council has stepped up its opposition to plans for a third bridge across the river Thames in Reading.
Berkshire's Reading, Wokingham and Bracknell councils all support the scheme in a bid to ease congestion.
But neighbouring Oxfordshire County Council has written a letter to Reading Borough Council opposing the scheme, outlined in its draft local transport plan.
Reading said it had a "very strong case" for the crossing.
Oxfordshire County Council and South Oxfordshire District Council had previously opposed the plans with concerns raised about a new bridge creating a "rat-run" for lorries that would usually travel on the A34 and M40.
The idea for a new bridge in the A3290 area to ease congestion in Reading town centre has been circulating for more than 40 years.
In its consultation response letter to Reading council, Oxfordshire council said it was "opposed to the plan in its present form, as we do not agree with the proposed schemes and measures it includes for cross boundary travel between Reading and Oxfordshire", according to the Local Democracy Reporting Service.
"The county council is particularly concerned about the approach proposed to develop large-scale 'multi-modal schemes' to the north of Reading, in particular the proposed Thames crossing, Reading orbital route and north of Reading park and ride sites," it added.
Tony Page, head of planning and transport at Reading council, said: "We will continue to press the very strong case for that crossing."
He previously accused Oxfordshire council of using "spoiler tactics" to prevent the plan from progressing.
Transport for South East, which plans strategic transport across the region, submitted a £800,000 bid to the Department for Transport (DfT) in October last year after prioritising the bridge project, which is expected to cost at least £110m.
DfT is yet to announce which projects will receive funding.
All affected councils are expected to meet next month to discuss the scheme.
There are currently three Thames bridge crossings in Berkshire - two in Caversham, Reading, and one in Sonning, Wokingham.