PM announces A47 study will also examine A12
A study of the A47 in the East of England will also look at improving the A12 between Norfolk and Suffolk, Prime Minister David Cameron has announced.
Mr Cameron, on a visit to the region, said the government has already invested £1.9bn into the East of England's infrastructure.
Norfolk MPs have been lobbying for the dualling of the whole of the A47.
Mr Cameron said he was committed to road improvements to boost business.
He visited Suffolk to see work taking place on dualling the A11.
"If you want to improve economic performance of regions and the country you have to look at transport links," he said.
"The big picture is we are spending £1.9bn in improving infrastructure in the East, that is more than any other region outside London and the South East.
"This a huge priority. Part of our long term economic plan is to have the infrastructure that Britain needs - the roads, the railways - to connect up our country to drive growth and create jobs and the wealth we need in our country."
He said the growth potential of the eastern region was "immense".
East of England Member of the European Parliament Richard Howitt (Labour) criticised Mr Cameron's visit.
"It is no good coming to our region saying nice things will happen, if there is no money to back it up," he said.
"This is a government that is scared of losing support in the East, coming here and offering nothing."
Campaigners say if the A47 is upgraded, in Norfolk alone 10,000 jobs could be created.
MPs, local councils and businesses have called on the government to invest £800m to upgrade the A47, which runs from Great Yarmouth to Peterborough.
The government said the A47 study is one of six projects around the country looking at ways "to find solutions to long-standing road hotspots".
Transport minister Robert Goodwill said: "The A47 and A12 are vital roads that give motorists and businesses access through the East of England and I want to ensure both provide the best service possible.
"These studies will ensure that investment will be targeted where it's most needed."