An economic body serving the whole of the Westcountry risks leaving Cornwall "strait jacketed", an MP has warned.
Local authorities this week revealed they are working up plans for a "Devonwall" Local Economic Partnership (LEP) to lobby for Government funding for Torbay, Devon, Plymouth, Cornwall and the Isles of Scilly.
Under the proposals, a separate coalition between just Cornwall and the Isles of Scilly would work together on economic development on a day-to-day basis.
Ties between the two counties have been strongly opposed by some in Cornwall over fears the interests of the far South West will be neglected. In the late 1990s, campaigners were successful in severing the formal link between the two counties after Cornwall was denied hundreds of millions of pounds of European regeneration cash.
St Ives MP Andrew George has warned against returning to a Devonwall structure to "avoid being strait jacketed by others".
The Liberal Democrat said: "Cornwall has achieved more in economic development terms in the last decade since it achieved separation from Devon and secured Objective 1 – now Convergence – status than it had in the decades before, when it followed the 'Devonwall' agenda.
"Don't get me wrong. Cornwall should always seek to work in partnership with others whether in Plymouth or Portsmouth, Devon or Devizes, Torbay or Taunton, on an issue-by-issue and project-by-project basis.
"But we mustn't lose control to others. Cornwall and Scilly do best when we stand on our own two feet. We do worse when we become dependent upon others."
Stephen Gilbert, Lib Dem MP for St Austell and Newquay, also warned that Cornwall risked losing control of its own destiny as a result of the tie-up.
He said: "Over the last decade Cornwall has achieved so much to develop the local economy by working as one, rather than the 'Devonwall' that it used to be.
"Our county is unique in so many ways and we have exceptional issues affecting us and distinctive challenges ahead."
A final decision on which submissions have proved successful will be taken by the Department for Business Innovation and Skills.
The LEPs will take over some of the functions of the soon-to-be-abolished regional development agencies and bid for funding from a central Government pot.
Advocates of a body covering the entire peninsula say it will have a stronger voice when battling with other regions for money.
Cornwall councillor Alex Folkes had tabled a motion in favour of a partnership independent of Devon. It was unanimously supported by his counterparts.