The Lake District is one of England's most visited areas
Extending the borders of the Lake District National Park could price local people out of the housing market, councillors have predicted.
Plans by Natural England could see the park extended to the south and east.
But Cumbria county councillors have rejected the proposals, claiming house prices on land within an extended national park would be forced up.
A three-month consultation exercise which began in December is due to end later this month.
A Cumbria County Council spokesman said: "Councillors have highlighted national parks having generally higher house prices, as a possible negative impact on people living in the areas that would become national parks."
'Beautiful and unspoiled'
Tim Knowles, Cumbria County Council's cabinet member for the environment, added: "While we do work closely and constructively with the national park authorities and Natural England, we feel we can't support proposals that will take decisions out of the hands of democratically-elected members and could have a negative impact on some of our local communities.
"The areas that Natural England are proposing become parts of the national parks are already beautiful and unspoiled areas of countryside and this won't change if they aren't incorporated into the national parks."
Natural England is also consulting on plans to extend the Yorkshire Dales National Park.
Confirmation of any new boundaries will be subject to approval by the government and a public inquiry .
The 885 sq mile (2,292 sq km) Lake District National Park came into being in August 1951.
It includes more than 30% of the county of Cumbria from Caldbeck in the north to Lindale in the south and from Ravenglass in the west to Shap in the east.