Authorities are currently being consulted on the format of the new organisation.
A report to Denbighshire UA says that with the voting patterns being suggested, 'South Wales authorities could dictate a pattern to North Wales which is unacceptable.'
And Paul Valerio, the Conservatives' Welsh local government spokesman said: 'Under these proposals, ourselves, Plaid Cymru and the Liberal Democrats will find it impossible at present to form a group. This is manifestly unfair.'
'I hope that the new organisation will work on a consensus basis because there is a community of interest across 90% of what we will discuss.'