Local Age Concerns that decide not to partner with Age UK could become embroiled in a legal row over the right to use the Age Concern name.
Age UK is currently asking the 332 local Age Concerns, which are independent charities, to become brand partners. But some Age Concerns, including Birmingham and Liverpool, are investigating plans to form an alternative organisation.
But it is unclear whether breakaway organisations could continue to use the Age Concern name. As a result, Birmingham and Liverpool have issued a joint statement calling on Age UK to clarify the situation.
The statement said: "There has not been any clear steer from Age UK as to the consequences of anyone continuing to use the name, even if their use of the name predates the current licensing agreement by decades."
Helena Herklots, services director at Age UK, said individual Age Concerns would "continue to have certain legal rights to use the individual Age Concern name", but added that the legal situation was complex.
"I would urge any local Age Concerns with any questions to come directly to us to discuss them," she said. "We have given all potential brand partners until 31 March 2011 to make a decision. We would not make any other plans about subsequent action required or take any steps to terminate existing brand licences until after that date."
To date, 37 Age Concerns have indicated they want to become brand partners with Age UK. Shirley Goode, chief executive of Age Concern Birmingham, said she had received about 30 inquiries from other Age Concerns interested in forming an alternative organisation.
Age UK was formed by the merger of Age Concern and Help the Aged.