Norwich South MP Clive Lewis has confirmed he has written to the county council to oppose all options for the Northern Distributor Road's proposed Western Link.
Conservative-run Norfolk County Council made the creation of a link, to connect the road now known as the Broadland Northway, the A47 to the west of the city a priority. It currently ends at the A1067.
The council recently consulted over four options, ranging in cost from £61m to £161m. Some options require a viaduct over the Wensum Valley and a bridge over the Tud Valley.
But Labour MP Mr Lewis, whose role as a shadow treasury minister involves him championing sustainable economics, has told County Hall is he is against all the options.
Norwich City Council's Labour cabinet had approved the principle of the road, so long as it comes with sustainable transport measures for Norwich.
Mr Lewis was not available to discuss his opposition, but a spokesman said: 'All of the options are likely to have an impact in increasing carbon emissions over a period of time. And all of the options threaten wildlife diversity.'
The spokesman added Mr Lewis had an issue with the government's system of awarding funding to transport schemes, saying it fuelled carbon reliant schemes.
A spokeswoman for Norfolk County Council said: 'The Western Link has a great deal of support in Norfolk – the two consultations we have carried out show the majority of people who responded agree a new or improved road link between Broadland Northway and the A47 is needed.
'We're aware that roads and communities to the west of Norwich are suffering from traffic congestion and rat-running and the Norwich Western Link will reduce this, and reduce journey times and improve quality of life for many people as a result.'
She added the council was 'committed' to minimising potential adverse impacts and had commissioned ecologists and environmental experts, while seeking advice from Natural England and the Environment Agency.
In February, Norfolk's seven Conservative MPs wrote to transport secretary Chris Grayling urging him to consider funding for the Western Link.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here