The main route linking Lynn with the rest of Norfolk and the Midlands is no longer fit for purpose, it has been claimed.
The warning was delivered on Friday as roads minister Robert Goodwill was driven along the A47 as part of the campaign for the route to be dualled.
Mr Goodwill has previously suggested that some money may be made available for upgrades later this year.
But West Norfolk councillor Vivienne Spikings, vice-chairman of the A47 Alliance, said: “Anyone who lives and works around King’s Lynn knows that the A47 is simply not fit for purpose in the 21st century.”
Toby Coke, chairman of Norfolk County Council’s transport committee, said the government should commit to funding the 19 improvement projects identified by the alliance earlier this year, with a longer-term commitment to a full dual carriageway.
He said: “The Government talks about infrastructure improvement, and it is needed here now.”
The minister’s visit co-incided with delays of up to 45 minutes for motorists using the road in the Lynn area as roadworks on the stretch between the Pullover and Hardwick roundabouts continue.